Stihl Ms 650, 660

Transcript

STIH) STIHL MS 650, 660 2007-09 Contents 1. Introduction 3 2. Safety Precautions 4 3. Specifications 5 3.1 3.2 3.3 3.4 3.5 Engine Fuel System Ignition System Chain Lubrication Tightening Torques 5 5 5 5 6 4. Troubleshooting Chart 4.1 4.2 4.3 4.4 4.5 4.6 5. Clutch, Chain Drive, Chain Brake, Chain Tensioner Rewind Starter Chain Lubrication Ignition System Carburetor Engine Clutch, Chain Drive, Chain Brake and Chain Tensioner 8 6. Engine 6.1 Muffler/Spark Arresting Screen 28 Shroud 29 Leakage Test 30 Preparations 30 Vacuum Test 31 Pressure Test 32 Oil Seals 32 Cylinder and Piston 34 Removing 34 Installing 36 Piston Rings 39 Crankcase/ Crankshaft 40 Removing the Crankshaft 40 Installing the Crankshaft 43 Decompression Valve 47 6.2 6.3 6.3.1 6.3.2 6.3.3 6.4 6.5 6.5.1 6.5.2 6.6 6.7 6.7.1 6.7.2 8 10 11 12 14 17 5.2 5.3 5.4 5.5 5.5.1 5.5.2 5.5.3 5.6 5.7 Clutch Drum / Chain Sprocket Replacing the Chain Catcher Spiked Bumper Clutch Chain Brake Checking Operation Removing Installing Chain Tensioner Bar Mounting Studs 9.1 Annular Buffers between Crankcase and Tank Housing 63 Annular Buffer at top of Tank Housing 64 9.2 10. 10.1 10.2 Master Control / Handle System 66 67 11. Chain Lubrication 68 11.1 48 7.1 7.2 7.2.1 Ignition Module Ignition Timing Removing and Installing Testing the Ignition Module Spark Plug Boot/ Ignition Lead Flywheel Removing Installing Contact Spring Testing Wiring Harness Ignition System Troubleshooting 48 48 49 11.3.2 12. Fuel System 7.6 51 52 52 53 53 54 55 Rewind Starter 58 8.1 8.2 General Removing and Installing Pawls Rope Rotor Starter Rope / Grip Tensioning the Rewind Spring Segment Starter Rope Guide Bushing Replacing the Rewind Spring 58 8.7 8.8 8.9 65 68 69 69 69 70 70 71 50 8. 8.3 8.4 8.5 8.6 65 10.3 Ignition System 7.3 7.3.1 7.3.2 7.4 7.5 63 Switch Shaft Throttle Trigger / Interlock Lever Front Handle 7. 7.2.2 19 19 20 22 22 22 24 27 28 AV System 11.2 11.2.1 11.2.2 11.3 11.3.1 18 18 9. Pickup Body / Suction Hose Valve Cleaning Replacing Oil Pump Removing and Installing Servicing 6.8 7.2.3 5.1 28 58 58 59 59 71 12.1 Air Filter 71 12.2 Carburetor 72 12.2.1 Removing and Installing 72 12.2.2 Leakage Test 74 12.3 Servicing the Carburetor 74 12.3.1 Metering Diaphragm 74 12.3.2 Inlet Needle 75 12.3.3 Fixed Jet 76 12.3.4 Pump Diaphragm 76 12.3.5 Removing and Installing the Throttle Shaft 77 12.3.6 Removing and Installing the Choke Shaft 79 60 61 61 62 q © ANDREAS STIHL AG & Co. KG, 2007 MS 650, MS 660 1 Contents 12.4 User Adjustment 12.4.1 Carburetor without Limiter Caps 12.4.2 Carburetor with Limiter Caps 12.5 Basic Setting (Carburetor with Limiter Caps) 12.6 Tank Vent 12.7 Pickup Body 12.8 Fuel Hose 12.9 Fuel Hose in Tank 12.10 Separating Crankcase and Tank Housing 12.11 Replacing the Tank Housing 80 90 13. Carburetor Heating 90 13.1 13.2 Testing 91 Troubleshooting Chart 93 14. Handle Heating System 80 81 82 84 86 87 87 88 94 14.1 14.2 14.3 Troubleshooting 94 Heater Switch 95 Heating Element in Rear Handle 96 14.4 Heating Element in Front Handle 97 14.5 Generator 97 14.5.1 Troubleshooting Chart 99 14.5.2 Test Connections and Test Values 101 15. Wiring Harness 15.1 Standard Wiring Harness 103 Wiring Harness with Handle and Carburetor Heating 104 15.2 16. 17. 2 103 Special Servicing Tools 106 Servicing Aids 108 MS 650, MS 660 1. Introduction This service manual contains detailed descriptions of all the typical repair and servicing procedures for this power tool. As the design concept of models MS 650 and MS 660 is almost identical, the descriptions and servicing procedures in this manual generally apply to both models. Differences are described in detail. You should make use of the illustrated parts lists while carrying out repair work. They show the installed positions of the individual components and assemblies. Refer to the latest edition of the relevant parts list to check the part numbers of any replacement parts. A fault on the machine may have several causes. To help locate the fault, consult the chapter on "Troubleshooting" and the "STIHL Service Training System" for all assemblies. Refer to the “Technical Information” bulletins for engineering changes which have been introduced since publication of this service manual. Technical information bulletins also supplement the parts list until an updated edition is issued. The special tools mentioned in the descriptions are listed in chapter "Special Servicing Tools" of this manual. Use the part numbers to identify the tools in the "STIHL Special Tools" manual which lists all the special servicing tools currently available from STIHL. Symbols are included in the text and pictures for greater clarity. The meanings are as follows: In the descriptions: : = Action to be taken as shown in the illustration (above the text) – = Action to be taken that is not shown in the illustration (above the text) +Situation applies from serial No. *SSituation applies up to serial No. Servicing and repairs are made considerably easier if the clamp (1) 5910 890 2000 is used to mount the machine on assembly stand (2) 5910 890 3100 so that one clamp screw engages the outer 10 mm hole (3) in the assembly stand. To service the underside of the machine (e.g. remove the front handle), turn it upside down and mount it so that one clamp screw engages the inner 10 mm hole in the assembly stand. Pull the hand guard back against the front handle for this purpose. In the illustrations: Pointer Direction of movement b 4.2 = Reference to another chapter, i.e. chapter 4.2 in this example. Always use original STIHL replacement parts. They can be identified by the STIHL part number, the STIH) logo and the STIHL parts symbol ( This symbol may appear alone on small parts. Service manuals and technical information bulletins are intended exclusively for the use of properly equipped repair shops. They must not be passed to third parties. MS 650, MS 660 3 2. Safety Precautions If the engine is started up in the course of repairs or maintenance work, observe all local and countryspecific safety regulations as well as the safety precautions and warnings in the instruction manual. Gasoline is an extremely flammable fuel and can be explosive in certain conditions. Improper handling may result in burns or other serious injuries. If parts are heated during servicing work, always wear suitable protective gloves. Do not bring any fire, flame, spark or other source of heat near the fuel. All work with fuel must be performed outdoors only. Spilled fuel must be wiped away immediately. 4 MS 650, MS 660 3. 3.1 Specifications Engine MS 650 Displacement: Bore: Stroke: Engine power to ISO 7293: Max. permissible engine speed with bar and chain: Idle speed: Clutch: Clutch engages at: Crankcase leakage test at gauge pressure: under vacuum: 3.2 84.9 cm3 91.6 cm3 52 mm 54 mm 40 mm 40 mm 4.8 kW (6.5 bhp) 5.2 kW (7.1 bhp) at 9,500 rpm at 9,500 rpm 13,500 rpm 13,500 rpm (carburetor with limiter caps) (carburetor with limiter caps) 13,000 rpm 13,000 rpm (carburetor without limiter (carburetor without limiter caps) caps) 2,500 rpm 2,500 rpm Centrifugal clutch without linings 3,000 rpm 3,000 rpm 0.5 bar 0.5 bar 0.8 bar 0.3 bar as specified in instruction manual Ignition System Air gap between ignition module and fanwheel: Spark plug (suppressed): Electrode gap: 3.4 0.5 bar 0.5 bar Fuel System Carburetor leakage test at gauge pressure: Operation of tank vent at gauge pressure: Fuel: 3.3 MS 660 0.15 – 0.3 mm Bosch WSR 6 F NGK BPMR 7 A 0.5 mm Chain Lubrication Fully automatic, speed-controlled oil pump with rotary piston Oil delivery rate: MS 650, MS 660 5.5 – 15 cm3 at 10,000 rpm 5 3.5 Tightening Torques DG and P screws (Plastoform) are used in polymer and light metal components. These screws form a permanent thread when they are installed for the first time. They can be removed and installed as often as necessary without impairing the strength of the screwed assembly, providing the specified tightening torque is observed. For this reason it is essential to use a torque wrench. Fastener Thread size For component Torque Remarks Nm Screw Starter post Screw Screw Screw Nut Twist lock Screw IS-M4x8 M8 M8x21.5 IS-M4x12 M10x 1 M4x10 M5 M5 IS-M4x12 Screw IS-P6x21.5 Screw Screw Screw Screw Screw Screw Screw IS-P6x19 IS-P6x19 IS-P4x19 IS-M4x 8 IS-M5x40x25 IS-M5x16 IS-M5 Screw IS-M5x20 Screw Screw Screw M5x12 IS-M5 IS-M5x20 Chain tensioner cover plate Starter post in fan housing Collar screw for guide bar Chain brake cover Decompression valve or plug Spring housing/fan housing Flange on filter base Filter cover Generator (for carburetor/handle heating only) Front handle, top, with stiffener (not wrap-around handle) Front handle, top (wrap-around handle) Front handle, bottom Handle molding Rubber buffer/crankcase Hand guard, left Shroud/crankcase Chain catcher/spiked bumper (with wrap-around handle) Chain catcher/spiked bumper/ crankcase Spiked bumper/crankcase, top with nut Chain sprocket cover/spiked bumper Crankcase/oil tank housing 3.0 12.0 23.0 3.0 14 2.5 2.0 1.0 3.5 1) 1) 7.0 7.0 7.0 1.6 3.5 7.0 7.0 6.0 9.0 7.5 6.0 11.5 Remarks: 1) Loctite 243, medium strength 6 MS 650, MS 660 Fastener Thread size For component Torque Remarks Nm Screw Screw Screw IS-M5x20 M12x1 L IS-M4x12 P6x19 IS-M5x16 IS-M5x12 IS-M5x20 M5x 6 IS-M6x20 M5x16 P4x10 M10x1 IS-M4x10 IS-M4x8 M5 M14x1.25 M5x20 M6x25 Screw M6x25 Screw Screw Screw Screw Screw Screw Screw Screw Screw Screw Screw Nut Fan housing, magnesium Clutch carrier Oil pump Annular buffer Annular buffer/tank housing, top right Annular buffer plate Wrap-around handle with bracket Muffler, bottom Muffler, bottom/crankcase Muffler/cylinder Guard/tank housing Flywheel Segment/fan housing Inner side plate Carburetor Spark plug Ignition module Cylinder/crankcase, 0.5 mm gasket Cylinder/crankcase, 1 mm gasket 7.0 70.0 3.0 6.0 7.0 9.0 7.0 6.5 15.0 11.5 2.0 45.0 2.5 3.0 3.5 25.0 8.0 15.0 3) 2) 1) 1) 1) 1) 1) 4) 15.0 Remarks: 1) Loctite 243, medium strength 2) Install with Hylomar sealant (0783 810 1101) 3) Left-hand thread 4) Degrease crankshaft/flywheel faces and install dry Use the following procedure when refitting a DG or P screw in an existing thread: Place the screw in the hole and rotate it counterclockwise until it drops slightly. Tighten the screw clockwise to the specified torque. This procedure ensures that the screw engages properly in the existing thread and does not form a new thread and weaken the assembly. Power screwdriver setting for polymer: DG and P screws max. 500 rpm Do not use an impact screwdriver for releasing or tightening screwed assemblies. Do not mix up screws with and without binding heads. MS 650, MS 660 7 4. 4.1 Troubleshooting Chart Clutch, Chain Drive, Chain Brake, Chain Tensioner Condition Cause Remedy Saw chain stops under load at full throttle Clutch shoes badly worn Install new clutch Clutch drum badly worn Install new clutch drum Brake band stuck Check freedom of movement and function of brake band. Engine idle speed too high Readjust with idle speed screw (LA) (counterclockwise) Saw chain rotates at idle speed Clutch springs stretched or fatigued Replace the clutch springs or install new clutch Clutch spring hooks broken Loud noises Chain sprocket wears rapidly 8 Replace the clutch springs Clutch springs stretched or fatigued Replace all clutch springs Needle cage damaged Fit new needle cage Clutch shoe retainer broken Fit new retainer Clutch shoes and carrier worn Install new clutch Chain not properly tensioned Tension chain as specified Wrong chain pitch Fit chain of correct pitch Insufficient chain lubrication Check chain lubrication Chain sprocket worn Fit new chain sprocket MS 650, MS 660 Condition Cause Remedy Saw chain does not stop immediately when brake is activated Brake spring stretched or broken Fit new brake spring Brake band stretched, worn or broken Fit new brake band Clutch drum worn Fit new clutch drum MS 650, MS 660 9 4.2 Rewind Starter Condition Cause Remedy Starter rope broken Rope pulled out too vigorously as far as stop or over edge, i.e. not vertically Fit new starter rope Normal wear Fit new starter rope Rewind spring broken Fit new rewind spring Spring overtensioned – no reserve when rope is fully extended Fit new rewind spring Very dirty or corroded Clean or replace rewind spring Guide peg on pawls or pawls themselves are worn Fit new pawls Spring clip fatigued Fit new spring clip Starter mechanism is very dirty Thoroughly clean complete starter mechanism Lubricating oil on rewind spring becomes viscous at very low outside temperatures (spring windings stick together) Coat rewind spring with a little standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons), then pull rope carefully several times until normal action is restored Starter rope does not rewind Starter rope can be pulled out almost without resistance (crankshaft does not turn) Starter rope is difficult to pull and rewinds very slowly 10 MS 650, MS 660 4.3 Chain Lubrication In the event of trouble with the chain lubrication system, check and rectify other sources of faults before disassembling the oil pump. Condition Cause Remedy Chain receives no oil Oil tank empty Fill up with oil Oil inlet hole in guide bar is blocked Clean oil inlet hole Intake hose or pickup body clogged or intake hose ruptured Fit new intake hose and pickup body Sealing ring between oil pump and crankcase faulty Remove oil pump, fit new sealing ring and reinstall pump Valve in oil tank blocked Clean or replace valve Teeth on pump piston and/or worm worn Install new oil pump Sealing ring between oil pump and crankcase faulty Remove oil pump, fit new sealing ring and reinstall pump Housing gasket faulty Fit new gasket Oil pump damaged or worn Install new oil pump Vent valve does not close Install new vent valve Adjusting screw and/or control edge on pump piston worn Fit new adjusting screw and/or oil pump Machine losing chain oil Oil pump delivers insufficient oil Intake hose or pickup body clogged Clean or replace intake hose/ pickup body Oil pump worn MS 650, MS 660 Install new oil pump 11 4.4 Ignition System Warning! Exercise extreme caution while carrying out maintenance and repair work on the ignition system. The high voltages which occur can cause serious or fatal accidents. Condition Cause Remedy Engine runs roughly, misfires, temporary loss of power Spark plug boot is loose Press boot firmly onto spark plug and fit new spring if necessary Ignition lead loose in ignition module Secure the ignition lead Spark plug sooted, smeared with oil Clean the spark plug or replace if necessary Too much oil in fuel mix, poor quality oil Fill up with fuel mix of specified quality Incorrect air gap between ignition module and flywheel Set air gap correctly Flywheel cracked or has other damage or pole shoes have turned blue Install new flywheel Ignition timing wrong, flywheel out of adjustment, key in flywheel has sheared off or is missing Install new flywheel, fit new key Weak magnetization in flywheel – pole shoes have turned blue Install new flywheel Crankcase damaged (cracks) Replace crankcase Faulty Master Control lever or ignition module Check operation of Master Control lever and ignition module No spark 12 MS 650, MS 660 Condition Cause Remedy No spark Faulty insulation or break in ignition lead or short circuit wire. Use ohmmeter to check ignition lead for break. If break is detected or high resistance measured, fit a new ignition lead; check short circuit wire for ground contact in run position Check operation of spark plug. Inspect Master Control lever, ignition coil/lead for damaged insulation and leakage current Clean or replace spark plug, replace faulty parts of ignition system MS 650, MS 660 13 4.5 Carburetor Condition Cause Remedy Carburetor floods; engine stalls Inlet needle not sealing. Foreign matter in valve seat or cone damaged Remove and clean or replace the inlet needle, clean the fuel tank, pickup body and fuel line if necessary Inlet control lever sticking on spindle Free off the inlet control lever Helical spring not located on nipple of inlet control lever Remove the inlet control lever and install it correctly Perforated disc on diaphragm is deformed and presses constantly against the inlet control lever Fit a new metering diaphragm Inlet control lever too high (relative to correct installed position) Replace inlet control system (lever, spindle, spring) Idle jet too lean Rotate low speed screw (L) counterclockwise (richer), (no further than stop on carburetors with limiter caps) Main jet too lean Rotate high speed screw (H) counterclockwise (richer), (no further than stop on carburetors with limiter caps) Inlet control lever too low (relative to correct installed position) Install new inlet control system (lever, spindle, spring) Inlet needle sticking to valve seat Remove inlet needle, clean and refit Diaphragm gasket leaking Fit new diaphragm gasket Metering diaphragm damaged or shrunk Fit new metering diaphragm Impulse hose damaged or kinked Fit new impulse hose Poor acceleration 14 MS 650, MS 660 Condition Cause Remedy Engine will not idle, idle speed too high Throttle shutter opened too wide by idle speed screw (LA) Set idle speed screw (LA) correctly Throttle rod sticking Check and free off throttle rod Oil seals/crankcase leaking Seal or replace oil seals/ crankcase Idle jet too rich or too lean Set low speed screw (L) correctly Setting of idle speed incorrect – throttle shutter completely closed Set idle speed screw (LA) correctly Small plastic plate in valve jet does not close Clean or renew valve jet Idle jet bores or ports blocked Clean the carburetor Engine stalls at idle speed MS 650, MS 660 15 Condition Cause Remedy Engine speed drops quickly under load – low power Air filter dirty Clean the air filter Throttle shutter not opened fully Check throttle rod Tank vent faulty Install new tank vent Fuel pickup body dirty Install new pickup body Fuel strainers dirty Install new fuel strainer Leak in fuel line between tank and fuel pump Seal connections or install a new fuel line Setting of high speed screw (H) too rich Rotate high speed screw (H) clockwise (leaner), no further than stop Main jet bores or ports blocked Clean the carburetor Pump diaphragm damaged or fatigued Fit new pump diaphragm Impulse hose damaged or kinked Fit new impulse hose 16 MS 650, MS 660 4.6 Engine Always check and, if necessary, repair the following parts before looking for faults on the engine: – – – – Air filter Fuel system Carburetor Ignition system Condition Cause Remedy Engine does not start easily, stalls at idle speed, but operates normally at full throttle Oil seals in crankcase damaged Replace the oil seals Crankcase leaking or damaged (cracks) Seal or replace the crankcase Piston rings worn or broken Fit new piston rings Muffler / spark arresting screen carbonized Clean the muffler (inlet and exhaust), replace spark arresting screen, replace muffler if necessary Air filter element dirty Replace air filter element Fuel / impulse hose severely kinked or damaged Fit new hoses or position them free from kinks Decompression valve sticking Replace the decompression valve Insufficient cylinder cooling. Air inlets in fan housing blocked or cooling fins on cylinder very dirty Thoroughly clean all cooling air openings and the cylinder fins Engine does not deliver full power or runs erratically Engine overheating MS 650, MS 660 17 5. 5.1 Clutch, Chain Drive, Chain Brake and Chain Tensioner Clutch Drum / Chain Sprocket 1 Wear work gloves to protect your hands from injury. 1 : Remove the E-clip (1). 100% 80% ! 148RA101 VA 1 178RA001 VA 2 178RA003 VA 2 3 : Inspect the clutch drum (1) for wear. : Remove the washer (2). : Unscrew the hex nuts (1). If there are signs of serious wear on the inside diameter of the clutch drum (1), check the remaining wall thickness. If it is less than about 80% of the original thickness, fit a new clutch drum. : Remove the chain sprocket cover (2). : Remove the bar (3) and chain. 1 178RA004 VA If the clutch drum has to be replaced, also check the brake band – b 5.5.2. : Disengage the chain brake by pulling the hand guard towards the front handle. 2 1 178RA005 VA 143RA004 VA : Remove the rim sprocket (1). : Remove the clutch drum (1) with needle cage (2). – Examine the needle cage for signs of damage. 18 MS 650, MS 660 5.2 Replacing the Chain Catcher 5.3 Spiked Bumper 1 Clean stub of crankshaft. Wash the needle cage, examine it for damage and replace if necessary. Lubricate needle cage with STIHL multipurpose grease – b 17. 1 178RA007 VA 2 178RA006 VA 178RA002 VA 2 3 – Remove the chain sprocket cover, chain and bar – b 5 – Remove the chain sprocket cover, chain and bar – b 5 : Take out the screw (1). : Hold the self-locking nut steady and take out the screw (1). : Remove the chain catcher (2). : Rotate clutch drum/chain sprocket and apply slight pressure at the same time until the oil pump drive spring engages the notch (see arrow). Reassemble in the reverse sequence. MS 650, MS 660 : Take out the screw (3). Reassemble in the reverse sequence. : Remove the spiked bumper (2) and chain catcher. Reassemble in the reverse sequence. 19 5.4 Clutch – Troubleshooting chart – b 4.1 1 – Remove the clutch drum/chain sprocket – b 5.1 : Pull the boot (1) off the spark plug. 178RA015 VA 178RA010 VA 1 : Unscrew the clutch (1) from the crankshaft clockwise (left-hand thread). – Unscrew the spark plug. 1 1 1 2 : Close the decompression valve (1). : Loosen the twist lock (1). : Remove carburetor box cover (2) to the rear. : Push the locking strip (1) 0000 893 5903 into the spark plug hole so that "OBEN-TOP" faces up. 178RA016 VA 178RA014 VA 178RA008 VA 2 : Remove the cover washer (1) and clean it if necessary (note the installed position of the cover washer). Disassembling the clutch 1 2 178RA009 VA 178RA017 VA 1 : Pull off the air baffle (1) upwards. 20 : Use hook (2) 5910 890 2800 to remove the clutch springs (1). MS 650, MS 660 2 1 3 2 – Pull the clutch shoes off the carrier. : Fit the clutch shoes over the arms (1) of the clutch carrier so that the series number (2) is on the same side as the longer hexagon (3). – Clean all parts – b 17. : Attach one end of each spring (1) to the clutch shoes. : Use the hook (2) 5910 890 2800 to attach other end of the spring and press it firmly into the clutch shoe. 178RA021 VA 208RA026 VA : Pull the retainers off the clutch shoes. 178RA2022VA 178RA020 VA 178RA018 VA 1 : Clamp the clutch in a vise. – Replace any damaged parts. Assembling the clutch 178RA019 VA 178RA023 VA 1 : Slip the retainers onto the clutch shoes. MS 650, MS 660 : Fit the cover washer (1) on the crankshaft so that its raised center (arrow) faces outwards. 21 : Screw home the clutch (1), hexagon facing outward, and tighten it down firmly – b 3.5 The clutch has a left-hand thread. – Remove locking strip from the cylinder. Reassemble all other parts in the reverse sequence. Contamination (with chain oil, chips, fine particles of abrasion, etc.) and smoothing of the friction surfaces of the brake band and clutch drum impair the coefficient of friction. This, in turn, reduces the frictional forces and thus prolongs the braking time. A fatigued or stretched brake spring has the same negative effect. – Start the engine. 2 1 138RA004 VA 178RA024 VA 1 5.5 Chain Brake 5.5.1 Checking Operation 5.5.2 Removing The chain brake is one of the most important safety devices on the chainsaw. Its efficiency is measured in terms of the chain braking time, i.e. the time that elapses between activating the brake and the saw chain coming to a complete standstill. The shorter the braking time, the better the efficiency and protection offered against being injured by the rotating chain. – Troubleshooting chart – b 4.1 – Remove the chain sprocket cover, chain, bar and clutch drum – b 5.1 : Take out the screw (1). : Remove the inner side plate (2). – Engage the chain brake by pushing the hand guard away from the front handle. – With the chain brake activated (locked), open the throttle wide for a brief period (max. 3 seconds) – the chain must not rotate. – With the chain brake released, open the throttle wide and activate the brake manually – the chain must come to an abrupt stop. The braking time is in order if deceleration of the saw chain is imperceptible to the eye. 178RA025 VA If the chain brake does not operate properly, see troubleshooting chart – b 4.1. : Take out the screws (arrows). : Remove the cover. 22 MS 650, MS 660 2 1 3 3 2 : Carefully ease the brake spring (1) off the anchor pin (2). : Remove the brake spring (1) from the brake lever (3). 2 Install a new brake band if there are noticeable signs of wear (large areas on inside diameter and/or parts of outside diameter) and its remaining thickness is less than 0.6 mm. : Remove the E-clip (1). The thickness of the brake band must not be less at any point. – Pull the lever out of the hand guard. : Pry the hand guard (2) together with the brake lever (3) off the pivot pin (arrow). If the brake band is still serviceable, use No. 120 emery paper or emery cloth (grain size approx. 120 µm) to clean and roughen its friction face (inside diameter). 178RA027 VA 1 4 178RA030 VA 178RA026 VA 178RA028 VA 1 : Pry the brake band (1) out of the crankcase. : Disconnect the brake band (1) from the brake lever (2). 1 : Take out the screw (arrow). 3 178RA031 VA 178RA029 VA 2 : Disconnect the spring (1). : Remove the E-clip (3). : Remove the lever (2) with spring (1). MS 650, MS 660 23 Clean all disassembled parts in standard solvent-based degreasant containing no chlorinated or halogenated hydrocarbons. – Inspect parts and replace if damaged. – Clean the entire housing recess for the chain brake. If the groove in the brake spring anchor pin is worn, follow the steps below to install a new pin: Do not drive out the pin in the other direction as this would damage the annular bead which was formed in the crankcase bore when the pin was originally installed. In such a case neither the new anchor pin nor the brake spring would locate properly. Furthermore, the crankcase could be damaged in this way and possibly impair correct operation of the chain brake. Installing 178RA033 VA 5.5.3 – If the brake spring anchor pin has been removed, coat the knurled shank of the new pin with Loctite before installing – b 17. 178RA032 VA : Position the new pin in the bore so that the knurling on the pin meshes with the existing knurling in the bore. Turn pin back and forth as necessary. – Remove the cylinder – b 6.5.1 : Use a suitable punch to drive the anchor pin (1) out of the crankcase, from the inside outwards. 24 MS 650, MS 660 Coat all sliding and bearing points with STIHL multipurpose grease – b 17. a 176RA036 VA 138RA012 VA Do not lubricate the brake band. : Carefully tap home the pin squarely to obtain dimension "a" (about 4.3–4.7 mm). : Insert the lever in the side of the hand guard bearing boss. The short arm of the brake lever must point to the top of the hand guard. Make sure the pin is installed completely square. – Install the cylinder – b 6.5.2 Coat all sliding and bearing points with STIHL multipurpose grease – b 17. 3 2 : Position bearing boss (arrow) of hand guard (2) against the pivot pin and fit the other side of the hand guard over the fan housing. 178RA029 VA 4 178RA030 VA 1 : Fit the screw (arrow) and tighten it down firmly – b 3.5 : Position the brake lever (3) against the pivot pin. : Press the cam lever (4) slightly downward and push the hand guard and bell crank onto their pivot pins. 3 : Fit the lever (2). : Fit the E-clip (3). : Fit the E-clip (1). 1 178RA031 VA 2 178RA027 VA 1 2 : Attach brake band (1) to brake lever (2) and push it into the crankcase. : Attach the spring (1). MS 650, MS 660 25 1 2 2 a 1 176RA046 VA 178RA035 VA 138RA004 VA b : The turns of brake spring must be tightly against one another in the relaxed condition. If this is not the case, replace the brake spring. : Use the assembly tool (2) 1117 890 0900 to attach the brake spring (1) to the anchor pin (arrow). : Fit the side plate (2) over the collar screws and push it against the crankcase. : Fit the screw (1) and tighten it down firmly. Check correct position of protective tube: – Mount the guide bar and chain sprocket cover. Tighten down nuts on the chain sprocket cover – b 3.5 a = 18 mm b = 33 mm 178RA025 VA – Check operation of chain brake – b 5.5.1 – Place cover in position. : Insert screws (arrows) and tighten them down firmly – b 3.5 – Install the clutch drum/chain sprocket – b 5.1 2 178RA034 VA 1 : Hook the brake spring (1) to the brake lever (2). 26 MS 650, MS 660 Chain Tensioner 2 – Remove the inner side plate – b 5.5.2 178RA038 VA 178RA036 VA 1 2 : Remove the cover plate. 3 176RA057 VA 5.6 1 : Inspect the teeth on the spur gear and adjusting screw (1), replace both parts if necessary. To do this, pull off the thrust pad (2) and unscrew the tensioner slide (3). : Rotate the spur gear clockwise until tensioner slide (1) butts against the thrust pad (2). Install in the reverse sequence. Always replace the adjusting screw and spur gear as a matching pair. 178RA039 VA Coat teeth of adjusting screw and spur gear with grease, b 17, before installing. : Pull out the spur gear. : Pull out the retainer (1). : Take out the screw (2). MS 650, MS 660 : Take out the tensioner slide with adjusting screw and thrust pad. 178RA042 VA 178RA040 VA 2 178RA037 VA 1 : When reassembling, check that O-ring (arrow) is fitted in spur gear and coat it with oil before fitting the spur gear. 27 5.7 Bar Mounting Studs 6. 6.1 Engine Muffler/Spark Arresting Screen Always check and, if necessary, repair the fuel system, carburetor, air filter and ignition system before looking for faults on the engine. 1 1 2 178RA043 VA 178RA045 VA – Troubleshooting chart – b 4.6 Removing : Inspect spark arresting screen (1) (if fitted). If necessary, bend back the retaining tabs (2) and pull out the screen. – Remove the chain sprocket cover, bar and chain – b 5.1 : Push stud puller (1) 5910 893 0501 over the collar stud as far as it will go. Use a 15 mm wrench to unscrew the collar stud counterclockwise. Only machines with spark arresting screen in top casing – Clean or replace the spark arresting screen if necessary. Installing 1 2 – Before installing, coat thread of collar stud with Loctite – b 17 Reassemble all other parts in the reverse sequence. 178RA044 VA – Install and tighten down the collar stud – b 3.5 : Take out the screw (1). : Remove the spark arresting screen (2) and clean or replace if necessary. 178RA046 VA 176RA006 VA All machines : Take out the screws (arrows). : Take out the screws (arrows). – Remove the top casing. – Remove the bottom casing. – Remove the gasket (if fitted). 28 MS 650, MS 660 6.2 Shroud 1 178RA013 VA 1 178RA011 VA 3 178RA047 VA 2 : Remove the gasket (1). – Unscrew the spark plug – b 5.4 – Clean the sealing faces. : Take out the screws (arrows). – Inspect the heat reflecting foil and replace if necessary – b 6.7.2 : Lift the shroud (1) away vertically. – Before fitting the shroud, check that cap (arrow) is properly seated. Always replace damaged caps and grommets in sets. – Fit the shroud and tighten down the screws firmly – b 3.5 Installing : Install a new gasket (2) with its bead (3) pointing outward. – Coat threads of screws with Loctite – b 17 – Tighten down the screws firmly – b 3.5 – Note different sizes of mounting screws when fitting top casing: Lower mounting screws are M6x20 and the upper mounting are M5x6. 178RA012 VA – Fit the bottom casing. – Before fitting the shroud, check that the cover (arrow) is properly seated on the decompression valve. – Fit the top casing. – Tighten down the screws firmly – b 3.5 MS 650, MS 660 29 6.3.1 Preparations Defective oil seals and gaskets or cracks in castings are the usual causes of leaks. Such faults allow supplementary air to enter the engine and upset the fuel-air mixture. This makes adjustment of the prescribed idle speed difficult, if not impossible. Moreover, the transition from idle speed to part or full throttle is not smooth. The crankcase can be checked thoroughly for leaks with the carburetor and crankcase tester and the vacuum pump. For systematic troubleshooting, always perform the vacuum test first and then the pressure test. 1 1 2 176RA012 VA Leakage Test 178RA048 VA 6.3 – Remove the shroud – b 6.2 : Fit the sealing plate (1) 0000 855 8106 between the muffler and cylinder exhaust port and tighten down the screws moderately. – Remove the decompression valve – b 6.8 : Install plug (1) 1122 025 2200 and tighten down to 25 Nm. The sealing plate must completely fill the space between the two screws. : Fit spark plug (2) and tighten it down firmly – b 3.5 – Remove the carburetor – b 12.2.1 – Remove muffler top casing – b 6.1. – Set the piston to top dead center. This can be checked through the inlet port. 1 : Back off the bottom casing screws (arrows) half way – b 6.1 30 178RA050 VA 178RA046 VA 2 : Check that the sleeve (1) and washer (2) are in place. MS 650, MS 660 Vacuum Test Oil seals tend to fail when subjected to a vacuum, i.e. the sealing lip lifts away from the crankshaft during the piston's induction stroke because there is no internal counterpressure. 176RA017 VA 1 A test can be carried out with the vacuum pump to detect this kind of fault. : Check that the pin (1) in the test flange 1128 850 4200 is in hole No. 1 (arrow), fit if necessary. 3 2 1 176RA018 VA 6.3.2 : Close the vent screw (1) on the pump. : Operate lever (2) until pressure gauge (3) indicates a vacuum of 0.5 bar. If the vacuum reading remains constant, or rises to no more than 0.3 bar within 20 seconds, it can be assumed that the oil seals are in good condition. However, if the pressure continues to rise (reduced vacuum in the crankcase), the oil seals must be replaced. 1 : Push the test flange (1) into position. : When fitting the test flange, make sure the pin locates properly in the impulse hose (2). 178RA052 VA 3 178RA051 VA 2 – After finishing the test, open the vent screw and disconnect the hose. – Preparations – b 6.3.1 : Connect suction hose (arrow) of vacuum pump 0000 850 3501 to nipple (arrow) of the test flange. – Continue with pressure test – b 6.3.3 : Fit the nuts (3) and tighten them down firmly. MS 650, MS 660 31 6.3.3 Pressure Test 6.4 – However, if the pressure drops, the leak must be located and the faulty part replaced. 178RA052 VA To find the leak, coat the suspect area with oil and pressurize the crankcase. Bubbles will appear if a leak exists. Oil Seals It is not necessary to disassemble the complete crankcase to replace the oil seals. Flywheel side – Remove the flywheel – b 7.3.1 – After finishing the test, open the vent screw and disconnect the hose of tester 1106 850 2905. – Preparations – b 6.3.1 – Remove the test flange. : Connect pressure hose (1) of tester 1106 850 2905 to nipple (arrow) on test flange. – Install the carburetor – b 12.2.1 – Loosen the muffler bottom casing screws and remove the sealing plate. – Take out the screws one at a time and refit with Loctite – b 17 1 – Tighten down the screws firmly – b 3.5 : Close vent screw (1) on the rubber bulb. 176RA019 VA 146RA063 VA – Mount the muffler top casing. – Unscrew the plug from the cylinder. – Install the decompression valve – b 6.8 : Remove the key (arrow) from the crankshaft. Reassemble all other parts in the reverse sequence. 1 : Pump air into the crankcase with rubber bulb until the gauge (arrow) indicates a pressure of 0.5 bar. If this pressure remains constant for at least 20 seconds, the crankcase is airtight. 32 2 1 178RA187 VA 176RA015 VA 1 : On machines with handle/ carburetor heating, take out the screws (1). : Remove the generator (2). MS 650, MS 660 1 1 178RA189 VA 176RA021 VA 176RA022 VA 1 – Free off the oil seal in its seat by tapping it with a suitable tube or a punch. : Use the press sleeve (1) 1108 893 2405 to install the oil seal. – Free off the oil seal in its seat by tapping it with a suitable tube or a punch. : Apply puller (1) 5910 890 4400 with No. 6 jaws 0000 893 3711. The seating face must be flat and free from burrs. : Apply puller (1) 5910 890 4400 with No. 3.1 jaws 0000 893 3706. – Clamp the puller arms. – Wait about one minute, then rotate the crankshaft several times. – Clamp the puller arms. – Install the generator (if fitted) and tighten down the screws firmly – b 3.5 Take care not to damage the crankshaft stub. – Pull out the oil seal. Take care not to damage the crankshaft stub. – The crankshaft sealing face and taper must be free from grease. Clean with a standard solventbased degreasant containing no chlorinated or halogenated hydrocarbons – b 17 – Install the flywheel – b 7.3.2. Reassemble all other parts in the reverse sequence. – Cleaning sealing face with standard solvent-based degreasant containing no chlorinated or halogenated hydrocarbons – b 17 – Thinly coat the outside diameter of the oil seal with sealant – b 17 – Lubricate sealing lips of oil seal with grease – b 17 – Thinly coat the outside diameter of the oil seal with sealant – b 17 – Slip the oil seal, open side facing the crankcase, over the crankshaft stub. – Pull out the oil seal. – Lubricate the sealing lips of the oil seal with grease – b 17 Clutch side – Remove the clutch drum – b 5.1 – Remove the oil pump – b 11.3.1 MS 650, MS 660 33 6.5 6.5.1 1 Before removing the piston, decide whether or not the crankshaft has to be removed as well. The crankshaft has to be blocked to remove the flywheel and clutch by resting the piston on the wooden assembly block with the cylinder removed or loosened. 178RA192 VA 178RA190 VA 1 : Push installing sleeve (1) 1118 893 4600 on to the crankshaft stub. : Use press sleeve (1) 1108 893 2405 to press home the oil seal. Cylinder and Piston Removing – Remove the shroud – b 6.2 – Remove the fan housing with rewind starter – b 8.2 – Remove the carburetor – b 12.2.1 – Install the oil pump – b 11.3.1 – Install the clutch drum, b 5.1 – Remove the decompression valve – b 6.8 – Remove the muffler – b 6.1 1 – Pull off the spark plug boot and unscrew the spark plug. 178RA191 VA Reassemble all other parts in the reverse sequence. : Slip the oil seal, open side facing the crankcase, over the crankshaft stub. – Remove the installing sleeve. 1 178RA050 VA 2 : Take the sleeve (1) out of the manifold. : Remove the washer (2). 34 MS 650, MS 660 – Pull the manifold (2) off the intake stub. – Inspect the cylinder for damage and scores and replace if necessary. 178RA194 VA – If a new cylinder has to be installed, always fit a new matching piston. Do not use pointed or sharp-edged tools for this job. – Before removing the piston, decide whether or not the crankshaft has to be removed as well. The crankshaft has to blocked to remove the flywheel and clutch by resting the piston on the wooden assembly block with the cylinder removed or loosened. : Remove the hookless snap rings from the piston. Wear safety glasses to protect your eyes when working with spring washers and snap rings. 2 1 176RA075 VA : Loosen the hose clamp (1). : Carefully lift the cylinder and, at the same time, push the manifold through the tank housing opening. 176RA074 VA 178RA196 VA 178RA193 VA : Take out the cylinder base screws through the holes (arrows) in the cylinder. 2 1 : Use the assembly drift (2) 1111 893 4700 to push the piston pin (1) out of the piston. – Remove the clutch – b 5.4 – Remove the flywheel – b 7.3.1 If the piston pin is stuck, tap the end of the drift lightly with a hammer if necessary. Hold the piston steady during this process to ensure that no jolts are transmitted to the connecting rod. 176RA071 VA – Remove the piston from the connecting rod and take the needle cage out of the small end. – Remove the cylinder gasket from the crankcase. – Inspect the piston rings and replace if necessary – b 6.6 : Carefully separate the cylinder gasket from the cylinder base. – Pull the cylinder off the piston. MS 650, MS 660 35 6.5.2 Installing 2 2 1 : Thoroughly clean the gasket seating surface (1). : Lubricate the needle cage (2) with oil and fit it in the small end. : Check installed position of piston: 1 = Arrow points to exhaust port (muffler) 2 = Flywheel 1 178RA053 VA 2 178RA041 VA 176RA076 VA 1 : Fit the piston pin (1) on the assembly drift (2) and slide it into the piston. – Heat the piston on an electric heating plate to approx. 60°C (140°F). 1 Wear suitable gloves to protect your hands from burn injuries. 178RA197 VA 249RA144 VA – Slip the piston over the connecting rod. : Fit a new cylinder gasket (1), curvature facing down, on the crankcase. : Remove the sleeve from installing tool 5910 890 2212. : Push the assembly drift 1111 893 4700, small diameter first, through the piston and small end (needle cage) and line up the piston. 36 2 1 249RA145 VA 178RA049 VA Note gasket thicknesses: - with tabs (arrows) = 0.5 mm, - without tabs = 1.0 mm : Attach the snap ring (1) to the magnet (2) so that the snap ring gap is on the flat side of the tool's shank. MS 650, MS 660 1 : Apply the installing tool 5910 890 2212 to the piston boss, hold the piston steady, center the tool shank exactly and press home until the snap ring slips into the groove. – Lubricate the piston and piston rings with oil. : Rest the piston (1) on the wooden assembly block (2) 1108 893 4800. 249RA147 VA : Remove the sleeve and slip it onto the other end of the shank. MS 650, MS 660 : Fit the snap rings so that their gaps are on the piston's vertical axis (they must point either up or down – see arrow). 178RA199 VA 249RA150 VA : Align the piston rings so that the radii at the ring gap meet at the fixing pin. 249RA148 VA : Stand the installing tool, sleeve downward, on a flat surface (wooden board) and press vertically downwards until the sleeve butts against the tool's shoulder. Inner pin must again point toward flat face. 178RA198 VA : Push the large slotted diameter of the sleeve over the magnet and snap ring. Position the sleeve so that the inner pin (1) points toward the flat face (2) of tool's shank. 2 176RA082 VA 212RA081 VA 1 249RA146 VA 2 : Push the manifold on to the intake port. : Pay attention to the correct installed position (arrow). 37 : Slide the cylinder over the piston, the clamping strap moves downwards at the same time. 1 2 178RA203 VA 1 178RA200 VA a – Remove the clamping strap and wooden assembly block. : Position the clamp (1) at an angle of 45° with the screw head (2) on the right. : To pull the manifold flange through the intake opening in the tank housing, wind a piece of string (1) (about 15 cm long) around the back of the flange and pass the ends of the string through the intake opening. : Tighten down the screw until the gap “a” between the two ends of the clamp is 5 – 6 mm. : Press the manifold down. 178RA201 VA 1 – Check correct installed position of piston rings. 178RA193 VA 178RA202 VA : Use the clamping strap (1) 0000 893 2600 to compress the rings around the piston. – Lubricate the inside of the cylinder with oil. – Line up the cylinder and cylinder gasket. : Line up cylinder as it will be in the installed condition. It is important to observe this point as the piston rings might otherwise break. : Insert the cylinder base screws (arrows), but do not tighten them down yet. 38 MS 650, MS 660 6.6 – Remove the piston – b 6.5.1 1 – Remove the rings from the piston. 178RA050 VA 176RA089 VA 2 : Pull the ends of the string outward. Piston Rings : Fit sleeve (1) in manifold. : Fit the washer (2) on the studs. The manifold flange is pulled through the carburetor housing intake opening without damaging the manifold. – Screw home the decompression valve and tighten it down firmly – b 3.5 – Check that the flange is properly seated in the carburetor housing. – Fit the spark plug and tighten it down firmly – b 3.5 – Install the carburetor – b 12.2.1 – Install the muffler – b 6.1 176RA091 VA – Fit the shroud – b 6.2 Reassemble all other parts in the reverse sequence. : Tighten down the cylinder base screws in an alternate pattern – b 3.5 176RA092 VA 176RA090 VA : Use a piece of old piston ring to scrape the grooves clean. : Install the new piston rings in the grooves so that the radii at the ends of the rings face upward. – Install the piston – b 6.5.2 MS 650, MS 660 39 6.7 6.7.1 Crankcase/Crankshaft Removing the Crankshaft – Remove the spiked bumper – b 5.3 1 1 2 – Remove the chain catcher – b 5.2 – Drain the oil tank. 178RA166 VA Dispose of fuels and lubricants properly in accordance with local environmental requirements. 178RA117 VA – Drain the fuel tank. : Take the sealing ring (arrow) out of the housing bore. : Push the rubber grommet (2) and wire (1) out of the housing. – Remove the oil suction hose – b 11.1 – Pull the short circuit wire and ground wire out of the housing. – Remove the oil seals – b 6.4 – Separate the crankcase and tank housing – b 12.10 – Remove the shroud – b 6.2 – Remove the fan housing with rewind starter – b 8.2 – Remove the ignition module – b 7.1 – Remove the piston – b 6.5.1 – Remove the flywheel – b 7.3.1 – On machines with handle heating and/or carburetor heating, remove the generator – b 14.5 – Remove the chain brake – b 5.5.2 – Remove the clutch – b 5.4 – Remove the muffler –, b 6.1 178RA204 VA – Remove the oil pump – b 11.3.1 : Pull the impulse hose off the connector (arrow). 40 MS 650, MS 660 2 2 : At the chain tensioner side of the crankcase, use a 4 mm drift (2) to drive the dowel pin out of the two halves of the crankcase. – Remove the chain tensioner – b 5.6 178RA207 VA 3 176RA107 VA 1 176RA106 VA 1 : Remove the gasket from the crankcase. : Back off the spindle (1) in service tool AS 5910 007 2205 all the way. : Slip service tool AS (2) over the two collar studs. : At the clutch side of the crankcase, use a 4 mm drift (2) to drive the dowel pin out of the two halves of the crankcase. : Turn the spindle (1) of the service tool clockwise until the crankshaft is pressed out of the ball bearing. 11 11 2 11 11 The two halves of the crankcase separate during this process. – Remove the service tool AS. 1 178RA208 VA 178RA206 VA : Fit the hex nuts (3) (for sprocket cover) and tighten them down by hand. – Unscrew the spindle of service tool ZS (1) 5910 007 2220 a little (left-hand thread) : Position the service tool ZS (1) 5910 893 2101 against the flywheel side so that number 11 is at the bottom. The cylinder flange faces up. 178RA205 VA : Fit three M5x72 screws (arrows) in the holes marked “11“ and tighten them down against the drilled plate. – Take the heat reflecting foil off the crankcase. : Remove the screws (arrows) from the two halves of the crankcase. MS 650, MS 660 41 If the crankcase has to be replaced, all the components still fitted must be removed and checked for damage. This involves the following operations: : Turn the spindle (1) counterclockwise until the crankshaft is pushed out of the ball bearing. – Remove the annular buffers – b 9.1 178RA210 VA 1 178RA209 VA 1 – Unscrew the bar mounting studs – b 5.7 : Use press arbor (1) 1122 893 7200 to press the ball bearing at the flywheel side out of the crankcase, from the outside inwards 1 1 1 2 212RA196 VA 178RA211 VA 176RA111 VA 2 : The crankshaft (1), connecting rod (2) and needle bearing form an inseparable unit. It must always be replaced as a complete unit. : Use the press arbor (1) 1124 893 7200 to press the ball bearing at the clutch side out of the crankcase, from the inside outwards. When fitting a replacement crankshaft, always install new oil seals and ball bearings. – Inspect both halves of the crankcase for cracks and replace if necessary. : Remove nipple of tank cap cord (1) from the slot (2). – Remove the tank cap. The crankcase must be replaced as a complete unit even if only one half is damaged. Check the condition of all other parts, replace if necessary and transfer to the new crankcase. If only the ball bearings are replaced, all rubber and polymer components, such as oil suction hose and annular buffers, may be left in position. 42 MS 650, MS 660 Installing the Crankshaft New crankcases are supplied with preassembled ball bearings and oil seals. It is necessary to stamp the machine’s serial number on the crankcase with 2.5 mm figure stamps. 212RA195 VA If the original crankcase is used again, remove all gasket residue and clean the mating surfaces thoroughly to guarantee a perfect seal. 2 178RA213 VA If only the ball bearings have to be replaced, make sure the annular buffers, suction hose and oil tank cap are removed before the crankcase is heated. 1 – Heat the area of the ball bearing seat on the flywheel side of the crankcase to about 120 °C (250 °F). – Wait for crankcase to cool down. : Fit nipple of tank cap cord (1) in the slot (2) and pull it forwards. Wear suitable gloves to protect your hands from burn injuries. : Push the ball bearing, open side (balls visible) facing the crankcase, into the crankcase by hand, from the inside outwards as far as stop. This operation must be carried out very quickly because the bearing absorbs heat immediately and begins to expand. 1 2 178RA091 VA 6.7.2 : Push the annular buffer home so that its annular groove (1) engages the housing rib (2). If a new crankcase is installed, the following additional operations are necessary: : Dowel pins (arrows) must be in position. If necessary, drive them into the flywheel half of the crankcase. MS 650, MS 660 178RA214 VA 178RA212 VA 1 : If it is not possible to heat the flywheel side of the crankcase, use press arbor (1) 1124 893 7200 to press home the ball bearing as far as stop. 43 1 1 178RA215 VA 178RA216 VA 176RA128 VA 2 – Heat the area of the ball bearing seat on the clutch side of the crankcase to about 120 °C (250 °F). : If it is not possible to heat the clutch side of the crankcase, use press arbor (1) 1124 893 7200 to press home the ball bearing flush with the inside of the crankcase. : Screw spindle of service tool ZS (2) 5910 893 2101 fully home and then screw the threaded sleeve (1) 5910 893 2421 onto the spindle as far as stop. Wear suitable gloves to protect your hands from burn injuries. – Lubricate tapered stub of crankshaft with oil. The ball bearing must be flush with the inside of the crankcase. It projects about 1 mm at the clutch side (at the oil pump). 1 – Wait for crankcase to cool down. : Push the annular buffer home so that its annular groove (1) engages the housing rib (2). 176RA129 VA This operation must be carried out very quickly because the bearing absorbs heat immediately and begins to expand. 2 178RA092 VA : Push the ball bearing, open side (balls visible) facing the crankcase, into the crankcase by hand, from the outside inwards as far as stop. : Place tapered stub of crankshaft in ball bearing at the flywheel side of the crankcase. 44 MS 650, MS 660 1 1 : Screw threaded sleeve (2) to thread (1) of crankshaft stub. : Hold the crankshaft steady, release the spindle counterclockwise and then unscrew the service tool, also counterclockwise. – Fit crankshaft stub in the ball bearing. 1 178RA221 VA 178RA218 VA – Lubricate straight stub of crankshaft (arrow) with oil. : To prevent the crankcase halves and gasket twisting, fit M5x72 screws (arrows) in two crankcase holes and tighten them down as far as stop. 1 : Hold the spindle steady and rotate the service tool counterclockwise until the drilled plate butts against the crankcase. 178RA222 VA 178RA220 VA 2 178RA217 VA 1 : Place new gasket (arrow) on the flywheel side of the crankcase. : The gasket is held in position by the pins (1). 178RA219 VA – Fit bar mounting studs at clutch side – b 5.7 : Turn the spindle clockwise until the crankshaft locates against the ball bearing. The connecting rod must point toward the cylinder flange while the crankshaft is being installed. MS 650, MS 660 45 – Screw the spindle (counterclockwise, left-hand thread) fully into the service tool AS 5910 890 2205. : Screw the spindle (left-hand thread) fully into the service tool AS 5910 890 2205. – Push the threaded sleeve over the crankshaft stub. : Hold the crankshaft steady and rotate the spindle counterclockwise to screw the threaded sleeve onto the crankshaft. 212RA220 VA 176RA138 VA 176RA137 VA 1 : Check alignment of crankcase halves relative to dowel pins, then rotate the spindle counterclockwise. Pull the crankshaft in until the two halves of the crankcase meet. – Unscrew the hex nuts. – Let go of the crankshaft. Hold the service tool steady and continue turning the spindle until the tool locates against the guide bar mounting face. – Unscrew the spindle clockwise and take away the service tool. – Take out the two M5x72 screws. 178RA205 VA – Fit the hex nuts (for chain sprocket cover) on the collar studs and screw them down finger-tight. : Fit the screws (arrows) and tighten them down firmly in an alternate pattern – b 3.5 46 MS 650, MS 660 6.8 – Install the chain tensioner – b 5.6 – Install the piston and cylinder – b 6.5.2 – Trim away any excess gasket material in the area of the cylinder mounting face. – Install the muffler –b 6.1 – Install the oil seals – b 6.4 – Install the fan housing with rewind starter – b 8.2 Decompression Valve 1 2 – Install the oil suction hose – b 11.1 176RA147 VA – Install the flywheel – b 7.3.2 – Install the ignition module – b 7.1 – Install the oil pump – b 11.3 – Remove the shroud – b 6.2 – Install the carburetor – b 12.2.1 – Install the tank housing – b 12.10 – Install the chain brake – b 5.5.3 – Install the wiring harness – b 15 – Install the clutch – b 5.4 : Remove the cover (1). – Clean both halves of the crankcase. : Unscrew the decompression valve (2). Reassemble in the reverse sequence. – Fit the decompression valve and tighten it down firmly – b 3.5 : Fit the cover (1). 176RA146 VA – Fit the shroud – b 6.2 : Stick the heating reflecting foil in position, without creases, so that it covers the housing wall at the clutch side. MS 650, MS 660 47 7. Ignition System 7.1 Ignition Module Ignition Timing Ignition timing is fixed and cannot be adjusted during repair or servicing work Exercise extreme caution when troubleshooting or carrying out maintenance and repair work on the ignition system. The high voltages that occur can cause serious or even fatal accidents. 2 1 176RA149 VA Troubleshooting on the ignition system should always begin at the spark plug – b 4.5 7.2 Since there is no mechanical wear in these systems, ignition timing cannot get out of adjustment as a result of wear. The ignition module accommodates all the components required to control ignition timing. There are two electrical connections on the coil body: : High voltage output (1) for ignition lead 2 1 178RA055 VA : Connector tag (2) for short circuit wire Testing in the workshop is limited to a spark test. A new ignition module must be installed if no ignition spark is obtained (after checking that wiring and stop switch are in good condition) The electronic (breakerless) ignition system basically consists of an ignition module (1) and flywheel (2). 48 MS 650, MS 660 Removing and Installing – Remove the shroud – b 6.2 3 – Remove the fan housing with rewind starter – b 8.2 1 2 178RA054 VA 1 54 : If necessary, use a suitable punch to drive the pin out of the wire retainer (1). : Secure ground wire (2) with screw (3). : Tighten down screws (3 + 4) moderately. – Remove the wire retainer. – If necessary, install the ignition lead, b 7.2.3, before fitting the wire retainer. 2 178RA058 VA 7.2.1 : Connect the short circuit wire (5). : Position the ignition lead (1) in the guide (arrow). – Coat threads of screws with Loctite 242, b 17, before installing. 1 4 Reassemble in the reverse sequence. 178RA056 VA 3 : Pull off the short circuit wire (1). : Take out the screw (2). : Remove the ground wire (3). : Take out the screw (4). – Remove the ignition module. If the ignition lead or spark plug boot is damage, install new parts – b 7.2.3. 178RA057 VA 178RA060 VA 1 : On machines with handle and/or carburetor heating, position the wire (1) under the ignition module. : Rotate the flywheel until the “N” mark (arrow) is in line with the top of the ignition module. 2 : Push the wire (2) into the wire retainer (arrow). MS 650, MS 660 49 7.2.2 3 1 Testing the Ignition Module To test the ignition module, use either the ZAT 4 ignition system tester 5910 850 4503 or the ZAT 3 ignition system tester 5910 850 4520. Warning! The engine may start and accelerate during the test. 3 178RA061 VA The ignition test refers only to a spark test, not to ignition timing. 2 : Crank the engine quickly with the rewind starter (min. 1,000 rpm) and check spark in the tester’s window (2). If a spark is visible, the ignition system is in order. If no spark is visible in the window (2), check the ignition system with the aid of the troubleshooting chart – b 7.6 : Slide the setting gauge (1) 1111 890 6400 between the arms of the ignition module and the flywheel. – Press the ignition module (2) against the setting gauge. : Tighten down the screws (3) firmly – b 3.5 3 – Remove the setting gauge and use a feeler gauge to check the air gap. It should be 0.2 mm. ZAT 3 – Fit the shroud – b 6.2 1 2 3 2 Using the ZAT 4 ignition tester 5910 850 4503 Using the ZAT 3 ignition tester 5910 850 4520 – Before starting the test, install a new spark plug in the cylinder and tighten it down firmly – b 3.5 – Before starting the test, install a new spark plug in the cylinder and tighten it down firmly – b 3.5 : Remove spark plug boot and connect it to the input terminal (1). : Remove spark plug boot and connect it to terminal (2). : Push the tester’s output terminal (3) onto the spark plug. – Set the Master Control lever to “#“ 50 5910 850 4520 208RA054 VA – Install the fan housing with rewind starter – b 8.2 212RA209 VA 1 : Attach ground terminal (1) to the spark plug. : Use adjusting knob (3) to set spark gap to about 2 mm. MS 650, MS 660 7.2.3 Spark Plug Boot/ Ignition Lead While using the ZAT 3, hold it only by the handle (4) or position it in a safe place. Keep fingers or other parts of your body at least 1 cm away from the spark window (3), high voltage connection (2), ground connection (5) and the ground terminal (1). Warning! High voltage – risk of electric shock. – Set the Master Control lever to “#“. 4 212RA236 VA 1 176RA157 VA 2 3 – Remove the ignition module – b 7.2.1 : Use suitable pliers to pull the leg spring out of the spark plug boot. : Pull the grommet (1) off the high voltage output (2). – Unhook the leg spring from the ignition lead. : Unscrew the ignition lead (3) from the contact pin and pull it out of the high voltage output. – Pull the boot off the ignition lead. : Remove the grommet and insulating tube (4) from the ignition lead. – Cut new ignition lead to a length of 185 mm. – Use a pointed tool to pierce the center of the ignition lead’s insulation, about 15 mm from the end of the lead. : Crank the engine quickly with the rewind starter (min. 1,000 rpm) and check sparkover in the tester’s window (3). Warning! The engine may start and accelerate during the test. If a spark is visible, the ignition system is in order. : Pull the cover off the spark plug boot. MS 650, MS 660 212RA291 VA 176RA158 VA If no spark is visible in the window (3), check the ignition system with the aid of the troubleshooting chart – b 7.6. : Pinch the hook of the leg spring into the center of the lead (arrow). 51 212RA292 VA 7.3 7.3.1 – Coat inside of spark plug boot with Press Fluid OH 723. Flywheel Removing – Slip the insulating tube and grommet over the ignition lead. – Remove the fan housing with rewind starter – b 8.2 – Pack the high voltage output with STIHL multipurpose grease – b 17 – Use locking strip to block the piston – b 5.4 Do not use either graphite grease or silicone insulating paste. – Screw the ignition lead into the ignition module. – Push the grommet over the high voltage output. : Push the ignition lead and leg spring into the spark plug boot. : Make sure the leg spring locates properly inside the spark plug boot. 178RA062 VA 176RA161 VA – Install the ignition module – b 7.2.1 : Use socket 5910 893 5610 (for torque wrench) to unscrew the flywheel nut (arrow). – Push the cover over the spark plug boot. 3 2 : Use a pointed tool to pierce the center of the other end of the ignition lead which screws into the module. 52 178RA063 VA 176RA162 VA 1 : Back off the thrust bolt (1) of puller (2) 1106 890 4501. : Screw puller into the flywheel (3). MS 650, MS 660 7.4 Contact Spring : Hold the puller steady and screw home the thrust bolt (1) until the flywheel is released. Degrease crankshaft stub, key and slot in flywheel hub with standard solvent-based degreasant containing no chlorinated or halogenated hydrocarbons – b 17 – Remove the carburetor – b 12.2.1 : Check that key (arrow) is properly seated. : Pull off the connector (arrow). 1 – Remove the puller from the flywheel. 178RA066 VA 138RA101 VA Installing 178RA064 VA 7.3.2 – Set the Master Control lever to CHOKE. – Fit the flywheel in position. – Fit and tighten down the flywheel nut firmly – b 3.5 : Pull off the flywheel. Reassemble all other parts in the reverse sequence 1 178RA067 VA 178RA065 VA – Set gap between ignition module and flywheel – b 7.2.1 : Push the contact spring down and past the cam (1). Inspect flywheel and magnet poles for signs of damage or blue discoloration. If you find any damage, install a new flywheel. 178RA068 VA 1 : Pry the contact spring (1) downwards off the pin and remove it sideways. MS 650, MS 660 53 7.5 Testing Wiring Harness – Inspect the flywheel for damage – b 7.3 1 – Check air gap between flywheel and ignition module – b 7.2.1 2 178RA069 VA 178RA071 VA 1 Installing : Fit the connector (1). : Position the contact spring below the pin (2). It neither of these checks reveals a fault, install a new ignition module – b 7.2.1 Reassemble in the reverse sequence. If the spark plug and ignition lead with spark plug boot are in order, check the resistance of the short circuit wire, ground wire and contact spring. – Remove the fan housing with rewind starter – b 8.2 : Disconnect short circuit wire (1). – Connect the ohmmeter to ground and the short circuit wire. 178RA129 VA – Set Master Control lever to “$“ : Clip the contact spring to the pin. The resistance measured must be about 0 Ω. If it is much higher, the reason is a break in the wire. The wire or contact spring has to be replaced. – Set Master Control lever to “#“ 178RA070 VA The resistance measured must be infinitely high. If not, fit a new short circuit wire. If no fault can be found, carry out further checks: : Pull the front end of the contact upwards onto the cam. 54 MS 650, MS 660 7.6 Ignition System Troubleshooting Engine does not run Master Control lever in position “#“? Check the spark plug: – Smeared with oil, black? – Sooted? – Electrode gap correct? – Contacts shorted? Clean the plug, reset or replace Check spark plug boot: – Firmly seated on plug (leg spring)? – Leg spring hook in center of ignition lead? – Boot damaged? If necessary, install new spark plug boot and/or leg spring Test ignition system with ZAT 3 or ZAT 4 (use ZAT 3 as main spark gap – see TI 32.94) 1 MS 650, MS 660 55 1 Powerful spark? yes no Check air gap and reset if necessary Check flywheel: Have pole shoes turned blue? Install new flywheel Disconnect short circuit wire from ignition module Check ignition lead: – Severe chafing? – Spark plug boot: Holes/cracks? – Resistance: spark plug boot to ground: spec. 1.5 – 12kΩ – Check resistance of ignition lead: spec. < 10 Ω, –If necessary, install new spark plug boot and/or ignition lead 2 56 3 MS 650, MS 660 2 3 Check operation of Master Control lever: – Short circuit wire chafed? – Contact gap (contact spring) – If necessary, install new ignition lead and/or contact spring – Re-connect short circuit wire Powerful spark? yes no Install new ignition module yes Check “#“/“$“ function on Master Control lever MS 650, MS 660 Engine runs no Look for fault in fuel system or carburetor, check engine for leaks, check position of flywheel on crankshaft 57 Removing and Installing 8.3 Pawls 1 146RA092 VA If the action of the starter rope becomes very stiff and the rope rewinds very slowly or not completely, it can be assumed that the starter mechanism is in order but plugged with dirt. At very low outside temperatures the lubricating oil on the rewind spring may thicken and cause the spring windings to stick together. This has a detrimental effect on the function of the starter mechanism. In such a case it is sufficient to apply a few drops of a standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons) to the rewind spring. 8.2 : Remove the screws (arrows) from the fan housing. – Remove the fan housing with rewind starter – b 8.2 – Carefully push the hand guard upwards. : Carefully ease the spring (1) off the starter post. Carefully pull out the starter rope several times and allow it to rewind until its normal smooth action is restored. – Pull the lower edge of fan housing away from the crankcase and remove it downwards. If clogged with dirt or pitch, the entire starter mechanism, including the rewind spring, must be removed and disassembled. Take particular care when removing the spring. Reassemble in the reverse sequence. 1 2 The hand guard is secured to the fan housing and crankcase with the IS-M5x40 screw. 146RA093 VA Rewind Starter General 178RA072 VA 8. 8.1 Clean all components – b 17. Before installing, lubricate the rewind spring and starter post with STIHL special lubricant – b 17. – Tighten down the screws firmly – b 3.5 : Pull the pawls (1 + 2) out of the rope rotor. – Lubricate pegs of new pawls with grease – b 17 Reassemble in the reverse sequence. 58 MS 650, MS 660 8.4 Rope Rotor 8.5 – Remove the fan housing with rewind starter – b 8.2 Relieving tension of rewind spring – Pull out the starter rope about 5 cm and hold the rope rotor steady. Starter Rope / Grip – Remove the starter rope or remaining rope from the rotor. – Remove the fan housing with rewind starter – b 8.2 – Remove remaining rope from the fan housing, if necessary. – Remove the segment – b 8.7 – Install a new starter rope – b 8.5 – Relieve tension of rewind spring – b 8.4 The rewind spring will not be under tension if the starter rope is broken. – While still holding the rope rotor steady, take three full turns off the rope rotor. – Pull out the rope with the starter grip and slowly release the rope rotor. The system will not be under tension if either the starter rope or rewind spring is broken. – Remove the pawls – b 8.3 178RA075 VA 1 176RA183 VA 2 : Fit the rotor on the starter post so that its lug (1) slips behind the inner spring loop (2). Machines with ElastoStart grip Reassemble all other parts in the reverse sequence. – Remove remaining rope from starter grip. : Pry the cap out of the grip. – Tension the rewind spring – b 8.6 : Remove the washer (1) from the starter post. 212RA206 VA 146RA094 VA 1 : Thread the new starter rope through the top of the starter grip. – Carefully pull the rope rotor off the starter post. MS 650, MS 660 59 8.6 Tensioning the Rewind Spring – Remove the fan housing with rewind starter – b 8.2 178RA073 VA 178RA079 VA – Relieve tension of rewind spring – b 8.4 : Thread the other end of the rope, from outside, through the guide bushing in the fan housing. : Hold the rope rotor steady. : Pull out the rope with the starter grip and straighten it out. – Hold the starter grip firmly to keep the rope tensioned. 178RA076 VA : Thread the end of the rope through the hole in the side of the rotor, pull it out. – Secure the rope with a simple overhand knot. 178RA077 VA : Make a loop in the starter rope. 178RA078 VA 178RA074 VA – Let go of the rope rotor and slowly release the starter rope so that it can rewind properly. : Grip the rope next to the rotor and use it to turn the rope rotor six times clockwise. : Pull rope back until knot locates in recess (arrow) in rope rotor. – Tension the rewind spring – b 8.6 60 MS 650, MS 660 8.7 Segment 8.8 Wear on the guide bushing is accelerated by the starter rope being pulled sideways. The wall of the bushing eventually wears through and the bushing becomes loose. 1 178RA081 VA 178RA080 VA Starter Rope Guide Bushing – Remove the fan housing with rewind starter – b 8.2 – Remove the rope rotor – b 8.4 : Take out the screws (arrows). : Pull out the segment (1) upwards. – Place the new bushing in the fan housing. When the starter rope is fully extended, it must still be possible to rotate the rope rotor at least another half turn before maximum spring tension is reached. If this is not the case, pull the rope out, hold the rope rotor steady and take off one turn of the rope. 178RA082 VA 1 Do not overtension the rewind spring as this will cause it to break. Installing – Install the fan housing with rewind starter – b 8.2 – Use a suitable tool to pry the damaged bushing out of the fan housing. : Engage tabs (1) in the slots (arrows). 178RA223 VA : The rewind spring is correctly tensioned when the starter grip sits firmly in the rope guide bushing (arrow) without drooping to one side. If this is not the case, tension the spring by one additional turn. : Insert the screw spindle (1) of the installing tool 0000 890 2201 through the bushing from inside the fan housing. Reassemble all other parts in the reverse sequence. MS 650, MS 660 61 8.9 Replacing the Rewind Spring – Troubleshooting chart – b 4.2 The replacement spring comes ready for installation and is secured in a frame. 1 1 178RA084 VA 178RA224 VA Removing Wear a face shield and work gloves. – Remove the rope rotor – b 8.4 : Fit the thrust sleeve (1), tapered end first, and the hex nut. Installing – Lubricate the spring with a few drops of STIHL special lubricant before installation –b 17 : Tighten down the hex nut until the bushing is firmly seated. : Position replacement spring with frame (1) in the fan housing. The installing tool flares the lower end of the rope bushing. : Position suitable tools on the recesses (arrows) and push the spring into its seat in the fan housing. – Remove the installing tool. 178RA083 VA Reassemble all other parts in the reverse sequence. If the rewind spring pops out during installation, fit it in the installing tool 1116 893 4800 as follows: : Use suitable pliers to grip the outer spring loop and lift it up. – Take the rewind spring out of the fan housing. 178RA085 VA – Remove any remaining pieces of spring from the fan housing. : Arrange the rewind spring as shown in the illustration. 62 MS 650, MS 660 9. AV System 9.1 Annular Buffers between Crankcase and Tank Housing : Position the anchor loop about 25 mm from the edge of the spring housing. – Remove the front handle – b 10.3 178RA088 VA 212RA285 VA The crankcase and tank housing are connected by vibration damping rubber buffers and springs. Damaged rubber buffers (annular buffers) and springs must always be replaced in sets. – Remove the air filter – b 12.2.1 – Remove the shroud – b 6.2 Removing at clutch side – Remove the fan housing with rewind starter – b 8.2 : Pry the plugs (arrows) out of the annular buffers. : Fit the rewind spring in the spring housing in the counterclockwise direction, starting from outside and working inwards. 178RA089 VA 138RA110 VA – Remove the chain catcher – b 5.2 : Take the screws out of the annular buffers. – Place the spring housing in the fan housing. – Press the spring loop into the recess in the fan housing at the same time. – Install the rope rotor – b 8.4 Reassemble all other parts in the reverse sequence. 178RA090 VA – Tension the rewind spring – b 8.6 : Pry the annular buffers (arrows) out of the crankcase. MS 650, MS 660 63 9.2 Annular Buffer at top of Tank Housing 1 2 Removing at flywheel side Installing at clutch side : Pry the plugs (arrows) out of the annular buffers. : Push the annular buffer (1) home from outside so that its groove engages the housing rib (2). 178RA093 VA 1 2 178RA092 VA 178RA086 VA 1 1 – Remove the crankcase from the tank housing – b 12.10 : Take out the screws (1). : Remove the annular buffer (2). 178RA087 VA – Take the screws out of the annular buffers. : Pry the annular buffers (1) out of the crankcase. Note: Coat annular buffers with STIHL Press Fluid before installing. 64 2 178RA091 VA 1 1 1 Reassemble in the reverse sequence. Installing at flywheel side : Push the annular buffer home from outside so that its groove (1) engages the housing rib (2). Reassemble all other parts in the reverse sequence. MS 650, MS 660 10. Master Control / Handle System 10.1 Switch Shaft 1 The Master Control lever moves the switch shaft to select the required function. Removing The following positions can be selected with the Master Control lever: – Remove the carburetor – b 12.2.1 178RA096 VA 212RA116 VA 1 2 3 4 178RA094 VA 1 2 2 : Disconnect the throttle rod (1) from the trigger (2). – Remove the air filter – b 12.1 – Put the throttle rod to one side. “RUN“ (2) is the normal operating position – Set Master Control lever to “CHOKE“. 1 : Pull the short circuit wire (1) sideways out of the switch shaft (2). “START“ (3) opens the throttle shutter slightly. The choke shutter is fully open (warm start) 2 “CHOKE“ (4) opens the throttle shutter slightly. The choke shutter is closed (cold start) 178RA097 VA “STOP“ (1) closes short circuit contact, interrupts ignition : Carefully swing the left end of the switch shaft (1) upwards and pull it out of the retainer (2). – Pull the retainer out of its guide. 1 178RA095 VA 2 : Take out the screw (1). – Remove the handle molding (2). MS 650, MS 660 65 10.2 21 2 Throttle Trigger / Interlock Lever 1 Installing : Attach the throttle rod (1) to the throttle trigger. : Fit the switch shaft (1) in the “STOP“ position, the contact spring (arrow) on top. 178RA101 VA 178RA100 VA 178RA098 VA 2 1 – Remove the air filter – b 12.1 : Take out the screw (1). – Fit the handle molding. : Remove the handle molding (2). – Connect short circuit wire to switch shaft. : Push the switch shaft into the mounts (2) on the housing. – Install the carburetor – b 12.2.1 1 – Check operation. 178RA102 VA Reassemble all other parts in the reverse sequence. 2 : Pull the throttle rod (1) sideways out of the trigger (2). – Move the Master Control to the “RUN“ position. : Engine the retainer (1). 66 178RA099 VA 1 178RA103 VA 1 : Remove the interlock lever (1). MS 650, MS 660 10.3 Front Handle 2 : Remove the throttle trigger (1) with torsion spring (2). : When installing, make sure the torsion spring is under the interlock lever and engages the notch (arrow). 178RA107 VA 178RA104 VA 138RA128 VA 1 : Take out the screws (arrows). 212RA130 VA 212RA129 VA : Remove the torsion spring from the throttle trigger. 178RA108 VA 1 : On machines with handle heating the wires (1) from the heating element must be in the guide (arrow) under the interlock lever. : Take out the screws (arrows). – Remove the front handle. Reassemble in the reverse sequence. Installing 1 2 Machines with handle heating 1 – Remove the front handle with heating element – b 14.4 178RA231 VA 178RA106 VA – Check the heating element – b 14.1 : Fit the interlock lever (1) so that it engages the throttle trigger (2) when operated (arrow). : Position the handle molding so that its front edge (arrow) engages the frame (1). Reassemble all other parts in the reverse sequence. MS 650, MS 660 67 11. 11.1 Chain Lubrication Pickup Body / Suction Hose Impurities gradually clog the fine pores of the filter with minute particles of dirt. This prevents the oil pump from supplying sufficient oil to the bar and chain. In the event of problems with the oil supply system, first check the oil tank and the pickup body. Clean the oil tank if necessary. 1 176RA232 VA 178RA112 VA 1 : Use hook (1) 5910 893 8800 to pull the pickup body out of the oil tank. : Grip the tab (arrow) of the suction hose with pliers and pull the grommet out of the bore. – Troubleshooting chart – b 4.3 Do not stretch the oil hose too much during this operation. Pickup body – Pull the pickup body out of the suction hose. – Fit a new pickup body. – Flush out the oil tank. Note: Take care no to damage the fuel hose. Do not use pointed tools. 178RA111 VA 178RA109 VA 1 Reassemble in the reverse sequence. : Unscrew the oil tank cap (1) and drain the oil tank. : Pull the suction hose with pickup body out of the crankcase. Collect chain oil in a clean container or dispose of it properly at an approved disposal site. Suction Hose – Remove the clutch – b 5.4 1 2 178RA113 VA – Remove the oil pump – b 11.3.1 : Pull the pickup body (1) off the suction hose (2). 68 MS 650, MS 660 11.2 Valve 11.2.1 Cleaning 11.2.2 Replacing A valve is installed in the tank wall to keep internal tank pressure equal to atmospheric pressure. – Remove the oil tank cap. – Insert the suction hose in the crankcase. 176RA242 VA 176RA236 VA – Drain the oil tank. Collect chain oil in a clean container or dispose of it properly at an approved disposal site. – Remove the inner side plate – b 5.5.2 – Remove the oil tank cap. – Drain the oil tank. – Lubricate grommet with a little oil. Collect chain oil in a clean container or dispose of it properly at an approved disposal site. : Use a blunt tool to push the suction hose into the crankcase so that the tab locates in its seat at the bottom right (arrow). Reassemble all other parts in the reverse sequence. – Remove the inner side plate – b 5.5.2 1 212RA142 VA : Use a 6 mm drift to carefully drive the valve out of its seat and into the oil tank. : Blow the valve (1) clear with compressed air (from outside to inside of tank). – Remove the old valve from the oil tank. Reassemble in the reverse sequence. – Flush out the oil tank. 178RA114 VA Reassemble in the reverse sequence. : Carefully insert the new valve in the housing bore from outside. Check the correct installed position. MS 650, MS 660 69 11.3 Oil Pump 11.3.1 Removing and Installing 178RA115 VA 212RA144 VA a : Use a 6 mm drift to carefully press home the new valve from outside until it is about 0.8 – 1.2 mm below the housing face (’a’ in illustration). 178RA117 VA 1 – Remove the clutch – b 5.4 : Replace the sealing ring (1). : Pull the worm with drive spring (arrow) out of the oil pump and off the crankshaft stub. Always use a new sealing ring. Reassemble all other parts in the reverse sequence. – Lubricate the worm with grease before installing – b 17 – Coat oil pump screws with Hylomar sealant – b 17 176RA245 VA Reassemble in the reverse sequence. : Take the drive spring off the worm. 1 178RA116 VA 1 : Take out the screws (1). – Pull off the oil pump. 70 MS 650, MS 660 11.3.2 Servicing 5 12. 12.1 Fuel System Air Filter Dirty air filters reduce engine power, increase fuel consumption and make starting more difficult. 1 The air filter should be cleaned when there is a noticeable loss of engine power. 2 178RA119 VA 76 7 3 178RA118 VA 4 1 Always check the suction hose and pickup body before disassembling the oil pump. : Remove the air filter (1). – Remove and clean the felt prefilter (machines with HD air filter). – Remove the oil pump – b 11.3.1 : Use a 2 mm drift to drive out the spring pin (1). – Knock out the filter or blow it clear with compressed air from the inside outwards. : Pull out the control bolt (2). : Remove the O-rings (3). : Pry out the plug (4). – In case of stubborn dirt, wash all parts of the filter in STIHL universal cleaner or a fresh, nonflammable cleaning solution (e.g. warm soapy water) and allow to dry. 1 2 178RA008 VA : Remove the pump piston (5) with spring (6) and washers (7). – Clean all parts and examine for serviceability – b 17 – Do not use a brush to clean the felt prefilter. Replace damaged filters. : Unscrew the twist lock (1). Always install new O-rings. : Remove the filter cover (2). – Lubricate the pump piston and worm with grease before installing – b 17 : When fitting the control bolt (2), press in the plug (4) against spring pressure. 178RA120 VA 1 178RA009 VA Reassemble in the reverse sequence. 1 : Pull off the air baffle (1) vertically. MS 650, MS 660 : Pull off the baffle (1) in the direction of the arrow. 71 12.2 Carburetor 12.2.1 Removing and Installing The following servicing procedures show a carburetor without limiter caps. The procedures are exactly the same on carburetors with limiter caps. 1 2 178RA124 VA 1 1 178RA121 VA 2 : Unscrew the nuts (arrows). – Open the throttle wide. : Pull off the flange (1). : Hold the throttle shaft (1) steady (arrow). 1 : Remove the filter base (arrow). – Remove filter base – b 12.1 – Wash the filter mesh in the filter base thoroughly in a fresh, nonflammable cleaning solution and blow out with compressed air. : Pull the grommet (1) off the adjusting screws and out of the housing. 178RA123 VA 178RA122 VA : Release the throttle trigger and take the rod (2) out of the throttle shaft. If filter mesh is damaged, install a new filter base. Reassemble in the reverse sequence. 178RA125 VA 1 Machines with carburetor heating : Remove the baffle plate (1). 72 MS 650, MS 660 1 : Pull the heating element off the studs. : Before fitting the carburetor, check that the sleeve (1) and washer (2) are in place. 178RA131 VA 178RA050 VA 178RA126 VA 2 : Fit the grommet so that the tabs (1) engage behind the inside of the housing. – On machines with carburetor heating, make sure that wiring is properly positioned – b 15.2 All machines 1 : Pull the fuel hose (1) off the carburetor. 178RA130 VA 178RA128 VA 2 1 : When pushing the carburetor into position, check that the impulse hose (1) is correctly seated. : Connect the fuel hose (2). 1 : Remove the carburetor. Reassemble in the reverse sequence. MS 650, MS 660 178RA124 VA 178RA127 VA 2 : Squeeze the throttle trigger and hook the rod (2) to the throttle shaft (1). 73 12.2.2 Leakage Test 12.3 Servicing the Carburetor 12.3.1 Metering Diaphragm In the case of problems with the carburetor or fuel supply system, also check and clean the tank vent – b 12.6. 3 2 1 1 2 1 143RA172 VA 2 1 : Push the fuel line (1) 1110 141 8600 onto the nipple (2) 0000 855 9200. 178RA139 VA – Remove the carburetor – b 12.2.1 249RA012 VA The carburetor can be tested for leaks with the carburetor and crankcase tester 1106 850 2905. : Push the nipple into the pressure hose of tester 1106 850 2905. – Remove the carburetor – b 12.2.1 : Close the vent screw (1) on the rubber bulb (2) and pump air into the carburetor until the pressure gauge (3) shows a reading of approx. 0.8 bar (80 kPa). – Remove sleeve from end cover. If this pressure remains constant, the carburetor is airtight. However, if it drops, there are two possible causes: : Remove the metering diaphragm and gasket from the carburetor or end cover. : Take out the screws (1). : Remove the end cover (2). 1. The inlet needle is not sealing (foreign matter in valve seat or sealing cone of inlet needle is damaged or inlet control lever sticking). Remove to clean – b 12.3.2 2. Metering diaphragm damaged, replace if necessary – b 12.3.1 – After completing the test, open the vent screw (1) and pull the fuel line off the carburetor. – Install the carburetor – b 12.2.1 – Push the fuel hose onto the elbow connector. : Push the fuel line with nipple onto the carburetor’s elbow connector. 178RA140 VA 178RA138 VA Reassemble all other parts in the reverse sequence. : Carefully separate the diaphragm and gasket. – Inspect diaphragm for damage and wear and replace if necessary. 74 MS 650, MS 660 12.3.2 Inlet Needle If the gasket and diaphragm are stuck to the carburetor, remove them very carefully. Reassemble in the reverse sequence. 1 178RA142 VA The diaphragm material is subjected to continuous alternating stresses and eventually shows signs of fatigue, i.e. the diaphragm distorts and swells and has to be replaced. : Fit the metering diaphragm (1) on the carburetor body so that the perforated plate faces the inlet control lever and the tab (arrow) points towards the adjusting screws. The gasket and metering diaphragm are held in position by integrally cast pegs. 1 1 178RA143 VA 1 – Remove the metering diaphragm – b 12.3.1 : Take out the screw (1). – Remove the inlet control lever with spindle. There is a small spring under the inlet control lever which may pop out during disassembly. – Fit the end cover. – Take out the inlet needle. 178RA141 VA – Insert the screws and tighten them down firmly – b 3.5 Reassemble all other parts in the reverse sequence. 212RA281 VA : Place the gasket on the carburetor body so that the tab (arrow) points towards the adjusting screws. The cast pegs (1) hold the gasket in position. : If there is an annular indentation (arrow) on the sealing cone of the inlet needle, fit a new inlet needle. Reassemble in the reverse sequence. MS 650, MS 660 75 12.3.3 Fixed Jet 12.3.4 Pump Diaphragm 3 1 4 : Fit the inlet needle (1). 1 178RA145 VA 178RA144 VA 2 1 2 178RA146 VA 1 1 1 – Remove the metering diaphragm – b 12.3.1 – Remove the carburetor – b 12.2.1 : Fit spring (2) in bore. : Unscrew the fixed jet (1). : Take out the screws (1). : Insert spindle (3) in the inlet control lever (4). Take care not to damage the jet. : Remove the end cover (2). – Engage clevis in annular groove on head of the inlet needle. Reassemble in the reverse sequence. – Press the inlet control lever down and secure it with the screw. Make sure the helical spring locates on the control lever’s nipple. 2 1 Note: The upper face of the inlet control lever must be flush with the top of the carburetor body (+/- 0.1 mm). 178RA147 VA – Check that inlet control lever moves freely. : Carefully remove the gasket (1) and pump diaphragm (2) from the end cover or carburetor body. – Install the metering diaphragm – b 12.3.1 178RA148 VA Reassemble all other parts in the reverse sequence. : Carefully separate the diaphragm and gasket. – Inspect diaphragm for damage and wear, install a new gasket. 76 MS 650, MS 660 12.3.5 Removing and Installing the Throttle Shaft The diaphragm material, inlet and outlet valves are subjected to continuous alternating stresses and eventually shows signs of fatigue, i.e. the diaphragm distorts and swells and has to be replaced. 3 178RA155 VA 178RA150 VA 2 1 1 : Place the gasket (2) on the end cover (1). – Remove the carburetor – b 12.2.1 : Place the diaphragm (3) on the end cover (1). : Take out the screw (1). : Line up the diaphragm and gasket so that they are centered by the cast pegs (arrows). 1 – Fit the carburetor on the end cover. : Inspect the fuel strainer (1) for contamination and damage. If necessary, remove it from the carburetor and clean or replace. 178RA156 VA 178RA149 VA The pump diaphragm, gasket and end cover are held in position by pegs on the end cover. – Fit screw and tighten it down firmly – b 3.5 Reassemble all other parts in the reverse sequence. – Set the throttle shaft to the full throttle position. : Carefully pull the throttle shutter out of the shaft. Reassemble in the reverse sequence. 1 178RA158 VA 2 : Unscrew the idle speed screw (LA) (1). : In idle position, lever (2) butts against carburetor (arrow). MS 650, MS 660 77 2 3 4 178RA160 VA : Take out the screw (1). Installing : Swing the clip (2) to the side and pull it off. : Push the spring (1) onto the throttle shaft (2) and engage it in position. : Check that the stamped digits face you when the throttle shutter is closed. The marks (arrows) must be parallel to the throttle shaft. 178RA157 VA 178RA159 VA 1 – Pull the throttle shaft out of the carburetor. Examine parts for damage and wear and replace if necessary. 2 1 : Push the throttle shaft into the carburetor and position the spring against the carburetor body. – Check that the center of the notch in the throttle shutter is in line with the hole in the carburetor body. – Fit the idle speed screw (LA). : Rotate the throttle shaft counterclockwise (tensioning the spring) until the lever (3) is above the edge (4) of the carburetor. – Install the carburetor – b 12.2.1 – Carry out user adjustment – b 12.4 : Push the throttle shaft fully home. – Fit the clip and secure it in position with the screw. – Turn the throttle shaft to the wide open position. – Fit the throttle shutter in the shaft. 78 MS 650, MS 660 12.3.6 Removing and Installing the Choke Shaft 2 1 – Remove the carburetor – b 12.2.1 3 Installing : Close the choke shutter (2) against spring pressure. : Take out the screw (1). – Remove the choke shutter. 178RA164 VA 1 178RA163 VA 1 178RA161 VA 2 : Push the spring (1) onto the choke shaft (2) and engage it in position. : Check that the stamped digits face you when the choke shutter is closed. The indentations (arrows) must be parallel to the choke shaft. : Fit the choke shaft, lever (3) pointing down, in the carburetor – below the idle speed screw (LA). : Check that the notch in the choke shutter points towards the end cover (1). : Position the spring against the edge of the carburetor body (arrow) and push home the choke shaft at the same time. – Install the carburetor – b 12.2.1 – Carry out user adjustment – b 12.4 – Fit the E-clip. – Rotate choke shaft against spring pressure to the choke position. – Fit the choke shutter. 178RA162 VA 1 : Remove the E-clip (1). – Pull out the choke shaft. Examine parts for damage an wear and replace if necessary. MS 650, MS 660 79 12.4 User Adjustment 12.4.1 Carburetor without Limiter Caps H 1 L L 178RA152 VA H Standard setting Adjusting idle speed Engine stops while idling – Adjust idle speed with a tachometer. Adjust specified engine speeds within tolerance of +/- 200 rpm. – Set the low speed screw (L) one full turn open. 1. Adjust engine speed with idle speed screw (LA) to 3,000 rpm. – Turn the idle speed screw (LA) clockwise until the saw chain begins to move. Then turn it back one quarter turn. 2. Turn low speed screw (L) counterclockwise to obtain maximum engine speed. Chain runs while engine is idling – Shut off the engine. – Check the air filter and clean or replace as necessary. – Check and clean or replace spark arresting screen (if fitted). – Check chain tension. : Carefully screw down both adjusting screws (H and L) until they are against their seats. Then make the following adjustments: : Open high speed screw (H) one full turn. If this speed is higher than 3,400 rpm, abort the procedure and start again with step 1. 3. Use the idle speed screw (LA) to set engine speed again to 3,000 rpm. 4. Set the engine speed to 2,500 rpm with the low speed screw (L). 5. Open the throttle wide and set maximum engine speed to 13,000 rpm with the high speed screw (H). – Set the low speed screw (L) one full turn open. – Turn the idle speed screw (LA) counterclockwise until the chain stops running. Then turn the screw another one quarter turn in the same direction. Erratic idling behavior, poor acceleration Erratic engine running behavior even though low speed screw (L) is set one full turn open. : Open low speed screw (L) one full turn. – Idle setting too lean. Turn the low speed screw (L) counterclockwise until the engine runs and accelerates smoothly. If no tachometer is available, do not turn the high speed screw (H) beyond the standard setting to make the mixture leaner. – It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). 80 MS 650, MS 660 12.4.2 Carburetor with Limiter Caps Chain runs while engine is idling Adjustments for operation at high altitude H 3/4 A minor correction may be necessary if engine power is not satisfactory when operating at high altitude. – Set the low speed screw (L) one quarter turn open. L 1/4 H L 178RA151 VA – Check standard setting. – Warm up the engine. – Turn high speed screw (H) very slightly clockwise (leaner). If the setting is made too lean there is a risk of engine damage due to insufficient lubrication and overheating. Standard setting The limiter caps must not be removed for the standard setting. – Check the air filter and clean or replace as necessary. – Check and clean or replace spark arresting screen (if fitted). – Turn the idle speed screw (LA) counterclockwise until the chain stops running. Then turn the screw another one quarter turn in the same direction. Erratic idling behavior, poor acceleration Erratic engine running behavior even though low speed screw is set one quarter turn open. – Idle setting too lean. Turn the low speed screw (L) counterclockwise, but no further than stop, until the engine runs and accelerates smoothly. – Check chain tension. – With this carburetor it is only possible to correct the settings of the high speed screw (H) and low speed screw (L) within fine limits. – It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). – Open the high speed screw (H) counterclockwise as far as stop. – Close the low speed screw (L) clockwise as far as stop, then open it one quarter turn counterclockwise. Adjusting engine idle speed Engine stops while idling – Set the low speed screw (L) one quarter turn open. – Turn the idle speed screw (LA) clockwise until the saw chain begins to move. Then turn it back one quarter turn. MS 650, MS 660 81 12.5 A minor correction may be necessary if engine power is not satisfactory when operating at high altitude. – Check standard setting. – Warm up the engine. – Turn high speed screw (H) very slight clockwise (leaner) no further than stop. L Perform the following operations: 1 2 After removing the limiter cap it is necessary to carry out the basic setting. 178RA154 VA Adjustments for operation at high altitude Basic Setting (Carburetor with Limiter Caps) The limiter caps have to be removed from the adjusting screws only if it is necessary to replace the high speed screw (H) or low speed screw (L), clean the carburetor or carry out the basic setting. : Use the puller to turn the limiter cap on the low speed screw L clockwise as far as stop, then turn it back one quarter turn so that its slot (1) is in line with the slot (2) in the carburetor body – limiter cap’s lug must be visible through the slot in the carburetor body. If the setting is made too lean there is a risk of engine damage due to insufficient lubrication and overheating. 178RA153 VA : Marks on limiter cap and segment are in alignment (arrow). Note: The lug is in line with the slot. On older machines, the limiter cap’s lug is at 90° to the slot. Align the lug relative to the slot by eye. 178RA241 VA : Screw puller 5910 890 4500 about 5 turns counterclockwise into the limiter cap. : Pull off the limiter cap. 82 MS 650, MS 660 – Pull off the limiter cap. : Screw puller 5910 890 4500 about 5 turns counterclockwise into the limiter cap. Note: Limiter caps that have been removed once are damaged and must not be re-used. After removing the limiter caps it is necessary to carry out the basic setting first. – Screw down both adjusting screws until they are against their seats. – Open the high speed screw (H) (1) one full turn. – Open the low speed screw (L) (2) one full turn. The basic setting of the carburetor is easier with the setting disk 5910 893 6600 fitted on the screwdriver. 1 2 178RA243 VA H 178RA245 VA 178RA244 VA 178RA242 VA 2 1 Adjusting idle speed (with tachometer) : Line up the limiter cap on the high speed screw (H) so that its slot is in line with the slot in the carburetor body – limiter cap’s lug must be visible through the slot in the carburetor body. – Check the air filter and clean or replace as necessary. : Marks on limiter cap and segment are in alignment (arrow). – Check chain tension. – Check the spark arresting screen and clean or replace as necessary. – Warm up the engine. Note: The lug is in line with the slot. On older machines, the limiter cap’s lug is at 90° to the slot. Align the lug relative to the slot by eye. MS 650, MS 660 83 12.6 Correct operation of the carburetor is only possible if atmospheric pressure and internal fuel tank pressure are equal at all times. This is ensured by the tank vent. Adjust specified engine speeds within tolerance of +/- 200 rpm. 1. Adjust engine speed with idle speed screw (LA) to 3,000 rpm. 2 1 If this speed is higher than 3,400 rpm, abort the procedure and start again with step 1. 3. Use the idle speed screw (LA) to set engine speed again to 3,000 rpm. 4. Set the engine speed to 2,500 rpm with the low speed screw (L). 5. Open the throttle wide and set maximum engine speed to 13,500 rpm with the high speed screw (H). 179RA232 VA 2. Turn low speed screw (L) counterclockwise to obtain maximum engine speed. Tank Vent : Line up limiter cap lug (arrow) with slot (1) in carburetor. In the event of trouble with the carburetor or the fuel supply system, always check and clean the tank vent. Check function by performing vacuum test on the tank via the fuel hose. – Remove the air filter – b 12.1 : Push the limiter caps onto the adjusting screws until they are flush with the carburetor body (2). – Remove the filter base – b 12.1 – Drain the fuel tank. Limiter caps that have been removed once are damaged and must not be re-used. Dispose of fuel properly in accordance with environmental requirements. If the setting is made too lean there is a risk of engine damage due to insufficient lubrication and overheating. 6. Install new limiter caps. 178RA128 VA 1 : Pull fuel hose (1) off the carburetor. 84 MS 650, MS 660 Vacuum test Pressure test : Connect vacuum pump (1) 0000 850 3501 to fuel hose (2) and create vacuum in fuel tank. : Connect carburetor and crankcase tester 1106 850 2905 (1) to the fuel hose. Equalization of pressure takes place via the tank vent. There must be no build-up of vacuum in the tank. In the event of a malfunction, install a new tank vent. – Squeeze the rubber bulb until the the pressure gauge shows a reading of 0.5 bar. If this pressure remains constant for at least 20 seconds, the tank, including the tank vent, is airtight. If it drops, the leak must be found and the defective part replaced. 178RA234 VA 1 178RA132 VA 2 1 178RA135 VA 1 : Remove the filter element (1). 1 178RA235 VA – Clean area around the tank vent. : Pull the valve (1) into the tank. Installing Version with connector and hose – Place the valve in the tank and carefully pull it into position from the carburetor housing. Reassemble all other parts in the reverse sequence – Test tank for leaks – b 12.6 178RA233 VA 1 : Pry off the connector (1). MS 650, MS 660 85 12.7 Tank vent on MS 650 and MS 660 from serial # 1 63 264 274 and 360 548 784 – Carefully pry out the tank vent (1). 1 178RA134 VA 178RA133 VA 1 Any impurities mixed with the fuel are retained by the pickup body (filter). The fine pores of the filter eventually become clogged with minute particles of dirt. This restricts the passage of fuel and results in fuel starvation. In the event of trouble with the fuel supply system, always check the fuel tank and the pickup body first. Clean the fuel tank if necessary. : Remove the grommet (1). Cleaning the fuel tank Take care not to damage the grommet. If grommet is damaged, install a new one. Installing Hold the tank vent during this operation to prevent it popping out. Pickup Body – Before installing, lubricate outside diameter of grommet with Press Fluid OH 723 0781 957 9000 or two-stroke oil. – Lubricate tank vent’s nipple with Press Fluid OH 723 0781 957 9000 or two-stroke oil before fitting it in the grommet. – Remove the fuel tank cap and drain the tank. – Pour a small amount of clean gasoline into the tank. Close the tank and shake the saw vigorously. – Open the tank again and drain it. Dispose of fuel properly in accordance with environmental requirements. : Fit tank vent in the guides (arrow) on the tank housing. Reassemble all other parts in the reverse sequence – Test tank for leaks – b 12.6 86 MS 650, MS 660 12.8 Fuel Hose 12.9 Fuel Hose in Tank Pickup Body – Remove the air filter – b 12.1 : Use hook (2) 5910 893 8800 to pull the pickup body (1) out of the fuel tank. – Remove filter base – b 12.1 178RA137 VA 178RA128 VA 1 176RA297 VA 1 1 – Remove the carburetor – b 12.2.1 – Remove the pickup body (1) – b 12.7 : Pull the fuel hose (1) off the carburetor. Do not stretch the fuel hose too much during this operation. – Remove the carburetor housing. : Pull the grommet (arrow) with hose out of the tank. – Pull the pickup body off the fuel hose. – Pull out the fuel hose. Note: Take care not the damage the fuel hose. Do not use pointed tools. – Replace the pickup body. Reassemble in the reverse sequence. 1 178RA136 VA Reassemble in the reverse sequence. : Carefully pry the fuel hose out of the grommet in the tank. When installing, make sure the flat side of the grommet points towards the cylinder. Before installing, lubricate outside diameter of grommet with Press Fluid OH 723 0781 957 9000 or two-stroke oil. – Test tank for leaks – b 12.6 MS 650, MS 660 87 12.10 Separating Crankcase and Tank Housing – Drain the fuel tank. 1 – Drain the oil tank. 2 1 Collect fuels and lubricants in clean containers or dispose of properly in accordance with regulations. 178RA168 VA 178RA166 VA – Remove the front handle – b 10.3 – Remove the shroud – b 6.2 : Push the wires (1) inwards through the grommet. – Remove the carburetor – b 12.2.1 : Take out the screw (1). – Remove the annular buffers at both sides – b 9.1 – Remove the fan housing with rewind starter – b 8.2 – Disconnect or remove the short circuit wire and ground wire from the ignition module – b 7.2.1 1 : Take the sleeve (1) out of the manifold and pull off the washer (2). 1 178RA169 VA 178RA050 VA 2 : Pull off the impulse hose (1). – Carefully separate the crankcase from the tank housing. – Replace the tank housing – b 12.11 Machines with handle heating and/or carburetor heating – Replace the crankcase – b 6.7 Note the following points when reassembling. – Remove the ignition module – b 7.2.1 178RA167 VA 1 178RA165 VA 1 : Push the manifold flange through the housing opening. : Pull connectors (1) out of guide (arrow) and disconnect. 88 MS 650, MS 660 1 : Make sure ring (arrow) is in position and not damaged. – Connect impulse hose (1) to engine housing. 178RA203 VA 2 178RA171 VA 178RA170 VA 1 : To pull the manifold flange through the intake opening in the tank housing, wind a piece of string (1) (about 15 cm long) around the back of the flange. – Examine rubber buffer (2) for damage. – Pass the ends of the string through the intake opening. 1 : Check the sleeve (1) for wear. : If necessary, use 7 mm punch to drive out the sleeve, from the outside inwards. – Impulse hose must not be twisted or kinked. : Thread the impulse hose through the bore and pull it in until its groove engages. – Wiring in carburetor housing – b 15 176RA089 VA – Drive home the sleeve with drift 1114 893 4700. 178RA172 VA 178RA175 VA – Press the manifold down. : Pull the ends of string outwards. Check that flange is properly seated in the tank housing. Reassemble all other parts in the reverse sequence. MS 650, MS 660 89 12.11 Replacing the Tank Housing 13. – Separate the crankcase/tank housing – b 12.10 – Remove the short circuit wire – b 15.1 – Remove the front handle – b 10.3 – Remove the fuel hose in the tank – b 12.9 – On machines with handle heating, remove the heater switch – b 14.2 – Remove the tank vent – b 12.6 Reassemble in the reverse sequence. – Remove the throttle trigger – b 10.2 Make sure the impulse hose and wires are correctly positioned without kinks. – Remove the switch shaft – b 10.1 – Test tank vent for leaks –b 12.6 – Remove the contact spring – b 7.4 Carburetor Heating Current is supplied via wires to the heating element installed between the heating plate and carburetor. Carburetor heating is controlled by a thermostatic switch on the heating plate. The carburetor heating system should be checked if running problems occur when the cold engine is idling or running at part load, particularly at temperatures below freezing. Idling problems with a hot engine are also an indication of a fault in the carburetor heating system. 1 178RA173 VA 2 : Pull tank cap cord (1) out of slot (2). – Remove the tank cap. 1 178RA174 VA 1 : Take out the screws (1). – Remove carburetor housing from tank housing. 90 MS 650, MS 660 13.1 Testing Complete system Test the thermostatic switch separately. – Remove filter base –b 12.1 – Set the ohmmeter to measuring range “Ω“. 50 3 30 20 20 5 10 10 5 1 178RA177 VA 0 10 0 If the temperature is lower than + 13 °C (55 °F), the thermostatic switch may close and produce false readings. 176RA314 VA The generator and heating element are checked in the following test which should be performed at an ambient temperature of at least + 20 °C (68 °F). : Clip one of the two test leads to the carburetor body and the other to a cylinder fin (ground). Thermostatic switch – If the system is in good condition the ohmmeter will indicate about 8 Ω in measuring range "Ω". : Clip test leads to the heating element’s connectors. To ensure good electrical contact, press the heating plate and the heating element against the carburetor during the measurement. At temperatures above + 20 °C (68 °F), the ohmmeter must indicate an infinitely high value in measuring range “Ω“. If the reading obtained is outside this tolerance, test each component separately. – Remove the heating element. Cool the switch down to below + 6 °C (42 °F). The ohmmeter must indicate a value of about 8 Ω in measuring range “Ω“. If a higher value is indicated, install a new heating element. 178RA176 VA 1 : Remove the wires from the retainer (arrow). : Push back the insulating tubes (1) and disconnect the pin and socket connectors. MS 650, MS 660 91 178RA178 VA Heating element – Remove the heating element. : Clip one test lead to the heating element, and the other test lead to the wire that goes to the heating element. If the heating element is in good condition the ohmmeter will show a reading of about 8 Ω in measuring range “Ω“. If the reading obtained is outside this tolerance, install a new heating element. Reassemble in the reverse sequence. Make sure the pin and socket connector is straight. 92 MS 650, MS 660 13.2 Troubleshooting Chart Measure resistance of heating element at temperature = +20°C (68°F) Resistance approx. 8 Ohm? no Replace heating element no Replace thermostatic switch no Replace thermostatic switch yes Check thermostatic switch Does thermostatic switch close between + 13°C (55°F) and + 6°C (43°F)? yes Does thermostatic switch open between + 6°C (43°F) and above + 13°C (55°F)? yes Carburetor heating system in order MS 650, MS 660 93 14. 14.1 Handle Heating System Troubleshooting 176RA209 VA There are two reasons for failures in the heating system: 1. A break in the circuit due to a faulty wire or component. : Separate the pin and socket connector. 2. A short circuit resulting from damage to the insulation. 176RA211 VA The entire handle heating system is maintenance-free and subject to practically no wear. Faults in the generator, heating elements and wiring are generally caused by mechanical damage. – Clip one ohmmeter test lead to the generator wire and the other test lead to the rear handle heating element wire. All electrical components of the handle heating system are connected in series with the ohmmeter. I 1 If no reading is obtained, there is a break in the circuit. 178RA179 VA 176RA338 VA o : The heating element in the rear handle may overheat and fail if it is not bonded firmly in position, i.e. completely flat (no creases). If the ohmmeter shows a very low value, there is a short circuit in one of the components. : Set the heater switch (1) to “#“ – Set the ohmmeter to “Ω“. – Set the Master Control lever to “$“ Tracing the cause of a fault If the system is in order, the ohmmeter will show a reading of about 10 Ω in measuring range “Ω“. In either case it is necessary to check each component separately, b 14.5.1. The generator wire remains disconnected from the heating element during this check. – After completing the test, reconnect the wires and push the insulating tube over the pin and socket connector. 176RA208 VA – Install the interlock lever and handle molding – b 10.2 – Remove the handle molding – b 10.1 : Push back the insulating tube (arrow) on the pin and socket connector of the wire between the generator and rear handle heating element. 94 MS 650, MS 660 14.2 Heater Switch 1 – Remove the carburetor – b 12.2.1 : Remove the heater switch (1) with connector tags (2) and ring (3) inwards. : Pull of the connector (2). 178RA237 VA 178RA183 VA 2 178RA181 VA 3 2 1 1 : Fit the heater switch (1) and line it up properly. – Fit the washer with nut from outside and tighten down firmly. : Pull off the connector (1). 3 4 178RA182 VA : Push back the rubber grommet (2) a little. 1 5 : Assemble the heater switch (1) with connector tags (2) and ring (3). : Pull the connector sleeve (1) out of the heater switch. : Position the heater switch with the groove (arrow) facing down. : The washer (4) and hex nut (5) are fitted from outside. 2 178RA238 VA 2 178RA236 VA 1 2 1 : Push the connector sleeve (1) into the switch. – Push the rubber grommet over the switch. – Position the wire under the contact spring (2) (arrow). – Check freedom of movement of contact spring. I 178RA180 VA o : Unscrew the nut (arrow) from the switch. – Remove the washer. MS 650, MS 660 95 14.3 2 176RA225 VA 1 178RA239 VA 1 Heating Element in Rear Handle 3 : Fit the short circuit wire (1) between the connector tags (2) and contact spring (3). Avoid creases. If the heating element is not fitted perfectly flat, heat transfer will be interrupted and the element may fail as a result of overheating. The ambient temperature during installation should not be less than + 15°C (59°F). Reassemble in the reverse sequence. – Remove the upper handle molding – b 10.1 : Slide the two insulating tubes (1) off the pin and socket connectors and separate the connectors. 176RA337 VA : Push the wires (1) onto the connector tags. : Take pressure pad and heating element out of the handle recess. – Position the wires under the impulse hose (2). Before fitting the new heating element, clean the surface inside the handle so that it is free from grease, dirt and moisture. – Install the carburetor – b 12.2.1 176RA227 VA 1 178RA240 VA 2 : Fit a new expanded rubber pressure pad on top of the heating element. The heating element must be completely covered. Reassemble all other parts in the reverse sequence. Check operation of heating element 1 176RA336 VA 2 Run the saw at maximum revs for no more than 30 seconds with the heating switched on. – Removing the backing from the new heating element. : Place heating element (1) in handle housing (2) and press firmly and uniformly into position, from the center outwards. 96 MS 650, MS 660 Heating Element in Front Handle The heating element in the front handle (handlebar) is not replaceable. A new handle must be fitted if the heating element is faulty. – Remove the carburetor – b 12.2.1 14.5 Generator – Pull the connector sleeve out of the heater switch – b 14.2 – Take grommet off the contact sleeve. 2 – Remove the front handle – b 10.3 – Remove the interlock lever – b 10.2 178RA186 VA 14.4 1 – Slide the insulating tube off the pin and socket connector of the wire between the front handle heating element and the rear handle heating element. – Remove the ignition module – b 7.2.1 – Remove the flywheel – b 7.3.1 : Pull the wires (1) out of the guide (arrow). 178RA185 VA 176RA228 VA : Push back the insulating tubes (2) and separate the pin and socket connectors. : Separate the pin and socket connector. : Take the connecting wires out through the grommet. – Take the wire out of its guide. Reassemble in the reverse sequence. – When installing, position the connecting wire in the handle molding under the contact spring and the switch shaft, 1 – Positioning the wiring – b 15.2 2 1 : Pull the wire (arrow) out of the insulating tube. : Take the wire out of the guide (arrow). – Pull the wire into the carburetor housing. : Take out the screws (1). 178RA187 VA 178RA184 VA 1 : Remove the generator (2). MS 650, MS 660 97 2 : Inspect the generator and poles (arrow) for cracks or other damage. If damage is found, replace the generator. 1 2 178RA188 VA 176RA239 VA 2 : Place the generator in position with the connecting wires (1) facing the crankcase. : Position the generator wire in the crankcase recess (arrow). : Push the guide into the crankcase bore. – Install screws (2) with Loctite 242 – b 17 178RA195 VA : Tighten down the screws firmly – b 3.5 Reassemble all other parts in the reverse sequence. – Positioning the wiring – b 15.2 : Inspect the magnet ring (arrow) in the flywheel for cracks or other damage. If damage is found, replace the flywheel. Reassemble in the reverse sequence. 98 MS 650, MS 660 14.5.1 Troubleshooting Chart Start yes Do both handles warm up? no Heater switch on “#“? yes no Turn on switch Measure resistance of individual heating elements with ohmmeter (On machines with carburetor pull connector pins of wires from heating element on carburetor out of round plug) Check rear handle heating element In good condition? Bonding OK? no Install new rear handle heating element yes Resistance of rear handle heating element about 1 Ω? no yes Check generator Resistance between engine ground and generator connection about 0.5 Ω? no Install new generator yes 1 MS 650, MS 660 2 3 99 1 3 2 Test ground wire between connector tags and crankcase no Install new ground wire no Install new front handle Resistance between connectors tags and crankcase about 0 Ω ? yes Pull connectors off heater switch Test front handle heating element Resistance about. 7 Ω? yes Check heater switch (contact sleeve against switch housing) Closed: about 0 Ω ? Open: Circuit interrupted no Install new heater switch yes (On machines with carburetor heating, refit connector pin of wire from heating element in the round plug) System in order 100 MS 650, MS 660 14.5.2 Test Connections and Test Values – The pin and socket connections of the wires in the rear handle must be disconnected to test the individual components separately. Ohmmeter connection (use either test lead) Resistance Ω If faulty Lead 1 Lead 2 Spec. Actual Cause Remedy Switch Switch terminal 1) Switch housing < 0.5 - Switch faulty Replace switch Connector tags Connector tags Ground 0 > 1.0 Poor ground connection Replace ground wire Heating element in rear handle Connector on wire from rear handle heating element Connector on wire from rear handle heating element 1.0 0.8...1.2 Heating element OK Component Heating element in front handle Generator 1) Connector on wire from front handle heating element Connector on red wire Ground Ground 7.0 0.5 - Break in wire, heating element damaged 0 Short circuit – damaged insulation Install new heating element or repair insulation 6.0...8.0 Heating element OK Install new front handle - Break in wire, heating element damaged 0 Short circuit – Repair damaged insulation insulation 0.3...1.0 Generator OK Pull out wire for this purpose MS 650, MS 660 101 Component Generator Generator 102 Ohmmeter connection (use either test lead) Resistance Ω If faulty Lead 1 Lead 2 Spec. Actual Cause Connector on yellow wire Ground 0.5 0.3...1.0 Generator OK Connector on yellow wire Connector on red wire 1.0 Remedy - Break in wire, Install new generator damaged generator 0 Short circuit – Repair damaged insulation insulation 0.8...1.8 Generator OK - Break in wire, Install new generator damaged generator 0 Short circuit – Install new damaged insulation generator MS 650, MS 660 15. 15.1 Wiring Harness Standard Wiring Harness – Remove the fan housing with rewind starter – b 8.2 1 – Remove the shroud – b 6.2 – Pull off the spark plug boot. 178RA225 VA 178RA227 VA – Remove short circuit wire and ground wire – b 7.2.1 : Pull the wiring harness out of the grommet. : Push the wiring harness into the guide (arrow). – Inspect grommet for damage. : Fit short circuit wire in retainer (1) on ignition module. Reassemble in the reverse sequence. 1 178RA166 VA 2 : Push the wire (1) out of the grommet (2). : Pry out the grommet. – Inspect grommet for damage. Positioning the wiring – Remove the air filter and filter base – b 12.1 – Ease the connector sleeve off the switch shaft – b 10.1 – Remove connector from contact spring – b 7.4 178RA226 VA – Remove the carburetor – b 12.2.1 : Position the short circuit wire and ground wire under the impulse hose. MS 650, MS 660 103 15.2 Wiring Harness with Handle and Carburetor Heating – Remove the fan housing with rewind starter – b 8.2 1 1 – Remove the shroud – b 6.2 178RA176 VA – Remove short circuit wire and ground wire – b 7.2.1 178RA228 VA – Pull off the spark plug boot. On machines with carburetor heating : Pull the connector (1) off the heater switch. : Pull the wires out of the guide (arrow). – Remove the upper handle molding – b 10.1 : Pull back the insulating tubes (1) and separate the connectors. – Remove the interlock lever – b 10.2 – Remove the carburetor – b 12.2.1 – Ease the connector sleeve off the switch shaft – b 10.1 1 178RA186 VA 2 : Pull wire (1) out of guide (arrow). : Separate the connectors (2) (single or double core). – Push the wire out of the grommet – b 15.1 – Pry out the grommet – b 15.1 – Inspect grommet for damage. – Remove the air filter and filter base – b 12.1 2 212RA244 VA 1 : Push back the insulating hose (1) and separate the connectors (2). 104 MS 650, MS 660 4 1 3 2 : Pull the wires out of the insulating tube (1). – Pull the wire into the carburetor housing. 5 51 178RA227 VA 6 178RA230 VA 212RA245 VA 1 : Push wiring harness into guide (arrow). Positioning the wiring : Position the short circuit wire (1) and ground wires (3) under the impulse hose (4). : Fit short circuit wire in retainer (1) on ignition module. – Check freedom of movement of contact spring (not restricted by wires on heater switch). : Position wire (2) to front handle under the contact spring. 1 178RA229 VA 178RA176 VA : Route wires to rear handle through the grommet (5) and insulating hose (6). : Pull the wiring harness out of the grommet. : Pull insulating tubes (1) over the wires. – Inspect grommet for damage. : Fit the wires of the carburetor heating system in the guide (arrow). – Remove wires of front handle heating system – b 14.4 Reassemble in the reverse sequence. 1 178RA186 VA 2 : Position generator wire (1) in the guide (arrow). : Pull insulating tubes (2) over the wires. MS 650, MS 660 105 16. Special Servicing Tools No. Part Name Part No. Application 1 2 3 4 5 0000 893 5903 5910 890 2800 117 890 0900 5910 893 0501 1106 850 2905 6 7 8 9 Locking strip Hook Assembly tube Stud puller M8 Carburetor and crankcase tester - Plug - Sealing plate - Flange Vacuum pump 4221 025 2200 0000 855 8106 1128 850 4200 0000 850 3501 10 11 12 13 14 15 16 17 18 19 Puller - Jaws (No. 6) - Jaws (No. 3.1 + 4) Press sleeve Installing sleeve Assembly drift Installing tool Wooden assembly block Clamping strap Service tool AS 5910 890 4400 0000 893 3711 0000 893 3706 1108 893 2405 1118 893 4600 0000 893 4700 5910 890 2212 1108 893 4800 0000 893 2600 5910 007 2205 20 21 Screw sleeve Service tool ZS (set) 5910 893 2409 5910 007 2200 22 23 24 25 26 - Washer Assembly drift Press arbor Screw sleeve Setting gauge 5910 893 2101 1122 893 7200 1124 893 7200 5910 893 2421 1111 890 6400 27 28 29 30 31 32 33 Ignition system tester ZAT 4 Ignition system tester ZAT 3 Socket for torque wrench 17 mm Puller Installing tool Installing tool Hook 5910 850 4503 5910 850 4520 5910 893 5610 1106 890 4501 0000 890 2201 1116 893 4800 5910 893 8800 Blocking the crankshaft Detaching springs from clutch shoes Attaching springs Removing bar mounting studs Testing crankcase and carburetor for leaks Testing crankcase for leaks Sealing exhaust port Leakage test Testing crankcase for leaks, testing tank vent Removing oil seals Removing oil seal(s) Removing oil seal(s) Installing oil seal Installing oil seal Removing and installing the piston pin Fitting hookless snap rings in piston Fitting piston Compressing piston rings Removing crankshaft (clutch side) Installing crankshaft Removing crankshaft (flywheel side) Removing crankshaft Removing ball bearings Installing ball bearings Installing crankshaft Setting air gap between ignition module and flywheel Testing ignition system Testing ignition system Releasing flywheel Removing flywheel Flaring rope guide bushing Installing rewind spring Removing pickup body 106 Rem. MS 650, MS 660 r No. Part Name Part No. Application 34 35 36 37 38 39 40 Fuel hose - Nipple Puller - Setting disk Drift Assembly stand Torque wrench 1110 141 8600 0000 855 9200 5910 890 4500 5910 893 6600 1114 893 4700 5910 890 3100 5910 890 0301 41 Torque wrench 5910 890 0311 42 Crimping tool 5910 890 8210 43 Screwdriver bit T 27 x 125 0812 542 2104 44 45 T-handle screwdriver T 27 x 150 Pliers, DIN 5254-A 19 5910 890 2400 0811 611 8380 Testing carburetor for leaks Testing carburetor for leaks Removing limiter cap Installing limiter cap Installing sleeve Holding saw for servicing/repairs 0.5 to 18 Nm Alternative: Torque wrench 5910 890 0302 with optical/acoustic signal 6 to 80 Nm Alternative: Torque wrench 5910 890 0312 with optical/acoustic signal Attaching connectors to electrical wires Removing and installing spline socket head screws with electric or pneumatic screwdrivers; tighten down screws with torque wrench IS-P screws (4 mm) Removing and installing external circlips Rem. 1) Remarks: 1) Use only for releasing P screws. MS 650, MS 660 107 17. Servicing Aids No. Part Name Part No. Application 1 Lubricating grease (225g tube) 0781 120 1111 Oil seals, oil pump drive, chain sprocket bearing, sliding and bearing points of brake band, pawl pegs 2 Ignition lead HTR (10 m) 0000 930 2251 3 STIHL special lubricant 0781 417 1315 4 Press Fluid OH 723 0781 957 9000 5 STIHL multipurpose grease 0781 120 1109 6 Medium-strength threadlocking adhesive (Loctite 243) (250 ml bottle) 0786 110 0101 7 Hylomar sealant 0783 810 1101 8 Standard commercial solventbased degreasant containing no chlorinated or halogenated hydrocarbons 108 Bearing bore in rope rotor, rewind spring in fan housing High voltage output on ignition module Oil pump Cleaning sealing faces MS 650, MS 660 englisch / english 0455 178 0123. M0. J7. Printed in Germany